9. Stockholders' Equity

        The following table summarizes, by statement of operations line item, stock-based compensation expense for the years ended March 31, 2015, 2014 and 2013 (in thousands):

                                                                                                                                                                                    

2000 Equity Incentive Plan

        In June 2000, the Company adopted the 2000 Equity Incentive Plan ("2000 Plan"). The 2000 Plan provides for a total maximum aggregate number of shares which may be issued of 27,980,000 shares. The 2000 Plan is administered by the Compensation Committee designated by the Board of Directors. The Compensation Committee's authority includes determining the number of incentive awards and vesting provisions. As of March 31, 2015, there were 3,206,800 shares available for future grant.

Stock Options

        The Company issues stock options under the 2000 Plan to employees, non-employee directors and consultants that vest and become exercisable over a four-year period and expire 10 years after the grant date. The Company uses a Black-Scholes valuation model to estimate the fair value of the options at the grant date, and compensation cost is recorded on a straight-line basis over the vesting period. Stock-based compensation expense is based on awards that are ultimately expected to vest and accordingly, stock-based compensation recognized is reduced by estimated forfeitures. Management's estimate of forfeitures is based on historical forfeitures. All options are subject to the following vesting provisions: one-fourth vest one year after the issuance date and 1/48th vest on the first day of each full month thereafter, so that all options will be vested on the first day of the 48th month after the grant date. Information relating to stock options for fiscal year ended March 31, 2015, is as follows:

                                                                                                                                                                                    

Black-Scholes Model Valuation Assumptions

        The Company calculated the estimated fair value of each stock option on the date of grant using the Black-Scholes valuation method and the following weighted-average assumptions:

                                                                                                                                                                                    

        The Company's computation of expected volatility for the fiscal years ended March 31, 2015, 2014 and 2013 was based on historical volatility. The expected life, or term, of options granted is derived from historical exercise behavior and represents the period of time that stock option awards are expected to be outstanding. Management has selected a risk-free rate based on the implied yield available on U.S. Treasury Securities with a maturity equivalent to the options' expected term.

        The following table provides additional information on stock options for the Company's fiscal years ended March 31, 2015, 2014 and 2013:

                                                                                                                                                                                    

        As of March 31, 2015, there was approximately $1.6 million of total compensation cost related to unvested stock option awards that is expected to be recognized as expense over a weighted average period of 2.3 years.

Restricted Stock Units and Performance Restricted Stock Units

        The Company issues restricted stock units under the 2000 Plan to employees, non-employee directors and consultants. The restricted stock units are valued based on the closing price of the Company's common stock on the date of issuance, and compensation cost is recorded on a straight-line basis over the vesting period. The related compensation expense recognized is reduced by estimated forfeitures. The Company's estimate of forfeitures is based on historical forfeitures. The restricted stock units vest in equal installments over a period of four years. For restricted stock units with four year vesting, one-fourth vest annually beginning one year after the issuance date. The restricted stock units issued to non-employee directors vest one year after the issuance date. The following table outlines the restricted stock and performance restricted stock unit ("PRSU") activity:

                                                                                                                                                                                    

        The following table provides additional information on restricted stock units for the Company's fiscal years ended March 31, 2015, 2014 and 2013:

                                                                                                                                                                                    

        As of March 31, 2015, there was approximately $1.4 million of total compensation cost related to unvested restricted stock units that is expected to be recognized as expense over a weighted average period of 2.1 years.

        PRSU activity is included in the above restricted stock units tables. In May 2014, the Compensation Committee of the Company's Board of Directors approved the new Performance Restricted Stock Unit Program, which is applicable to certain senior employees. The Compensation Committee granted 200,000 PRSUs to the Chief Executive Officer under the 2000 Plan. The Chief Executive Officer is the only participant for Fiscal 2015. For the first year of the program, the PRSU grant for the Chief Executive Officer is broken out into two performance measurement periods. The first performance measurement period began on April 1, 2014 and will end on March 31, 2016; the second performance measurement period has a three-year term that began on April 1, 2014 and will end on March 31, 2017. Any earned PRSU awards will vest 50% after the end of the applicable performance measurement period and 50% one year thereafter.

        The weighted average per share grant date fair value of PRSUs granted during the fiscal year ended March 31, 2015 was $1.56. Based on our assessment as of March 31, 2015, the PRSU threshold for the first performance measurement likely will not be met and, as a result, the Chief Executive Officer PRSU awards were adjusted and no compensation expense was recorded or recognized during Fiscal 2015. Any compensation expense will be recognized over the corresponding requisite service period and will be adjusted in subsequent reporting periods if the Company's assessment of the probable level of achievement of the performance goals changes. The Company will continue to periodically assess the likelihood of the PRSU threshold being met until the end of the applicable performance period.

Non-employee Directors Stock Awards

        The Company issues stock awards under the 2000 Plan to non-employee directors who elected to take payment of all or any part of the directors' fees in stock in lieu of cash. The following table outlines the non-employee directors stock activity for the Company's fiscal years ended March 31, 2015, 2014 and 2013:

                                                                                                                                                                                    

        For each term of the Board of Directors (beginning on the date of an annual meeting of stockholders and ending on the date immediately preceding the next annual meeting of stockholders), a non-employee director may elect to receive a stock award in lieu of all or any portion of their annual retainer or committee fee cash payment. The shares of stock were valued based on the closing price of the Company's common stock on the date of grant.

2000 Employee Stock Purchase Plan

        In June 2000, the Company adopted the 2000 Employee Stock Purchase Plan (the "Purchase Plan"), which provides for the granting of rights to purchase common stock to regular full and part-time employees or officers of the Company and its subsidiaries. Under the Purchase Plan, shares of common stock will be issued upon exercise of the purchase rights. Under the Purchase Plan, an aggregate of 900,000 shares may be issued pursuant to the exercise of purchase rights. In August 2010, the Board of Directors adopted and the stockholders approved an amendment and restatement of the Purchase Plan. The amendment and restatement includes an increase of 500,000 shares of common stock that will be available under the Purchase Plan and extends the term of the Purchase Plan for a period of ten years. As amended, the Purchase Plan will continue by its terms through June 30, 2020, unless terminated sooner, and will reserve for issuance a total of 1,400,000 shares of common stock. The maximum amount that an employee can contribute during a purchase right period is $25,000 or 15% of the employee's regular compensation. Under the Purchase Plan, the exercise price of a purchase right is 95% of the fair market value of such shares on the last day of the purchase right period. The fair market value of the stock is its closing price as reported on the Nasdaq Global Market on the day in question. During the fiscal years ended March 31, 2015, 2014 and 2013, the Company issued a total of 20,619 shares, 12,302 shares and 22,478 shares of stock, respectively, to regular full and part-time employees or officers of the Company who elected to participate in the Purchase Plan. As of March 31, 2015, there were 409,569 shares available for future grant under the Purchase Plan.

Grants outside of the 2000 Plan

        As of March 31, 2015, the Company had outstanding 3,800,000 non-qualified common stock options and 93,750 restricted stock units issued outside of the 2000 Plan. The Company granted 250,000 of these stock options during Fiscal 2015, 250,000 of these stock options during Fiscal 2013, 3,300,000 of these stock options prior to Fiscal 2013, 62,500 of these restricted stock units during Fiscal 2015 and 31,250 of these restricted stock units during Fiscal 2013 as inducement grants to new officers and employees of the Company, with exercise prices equal to the fair market value of the Company's common stock on the grant date.

                                                                                                                                                                                    

        Although the options and restricted stock units were not granted under the 2000 Plan, they are governed by terms and conditions identical to those under the 2000 Plan. All options are subject to the following vesting provisions: one-fourth vest one year after the issuance date and 1/48th vest on the first day of each full month thereafter, so that all options will be vested on the first day of the 48th month after the grant date. All outstanding options have a contractual term of ten years. The restricted stock units vest in equal installments over a period of four years.

Stockholder Rights Plan

        The Company has entered into a rights agreement (as amended, the "Rights Agreement") with Computershare Inc., successor-in-interest to Mellon Investor Services LLC, as rights agent. In connection with the rights agreement, the Company's board of directors authorized and declared a dividend distribution of one preferred stock purchase right for each share of the Company's common stock authorized and outstanding. Each right entitles the registered holder to purchase from the Company a unit consisting of one one-hundredth of a share of Series A Junior Participating Preferred Stock, par value $0.001 per share, at a purchase price of $10.00 per unit, subject to adjustment. The description and terms of the rights are set forth in the rights agreement. Initially, the rights are attached to all common stock certificates representing shares then outstanding, and no separate rights certificates are distributed. Subject to certain exceptions specified in the Rights Agreement, the rights will separate from the common stock and will be exercisable upon the earlier of (i) 10 days following a public announcement that a person or group of affiliated or associated persons has acquired, or obtained the right to acquire, beneficial ownership of 20% or more of the outstanding shares of common stock, other than as a result of repurchases of stock by the Company or certain inadvertent actions by institutional or certain other stockholders, or (ii) 10 days (or such later date as the Company's Board of Directors shall determine) following the commencement of a tender offer or exchange offer (other than certain permitted offers described in the rights agreement) that would result in a person or group beneficially owning 20% or more of the outstanding shares of the Company's common stock.

        On July 1, 2014, the Company's Board of Directors unanimously approved a third amendment to the Rights Agreement pursuant to a "sunset provision," which was approved by the stockholders at the 2014 annual meeting. The third amendment amends the Rights Agreement to provide that the rights will expire on the 30th day after the 2017 annual meeting of stockholders unless continuation of the Rights Agreement is approved by the stockholders at that meeting. On August 5, 2014, the Company entered into a fourth amendment to the Rights Agreement. The fourth amendment amends the Rights Agreement to clarify that the term of the Rights Agreement may not be continued or extended unless and until such amendment has received the approval of the stockholders of the Company at an annual or special meeting of the stockholders held prior to the termination of the Rights Agreement without taking into account such amendment.

        The Rights Agreement is intended to protect the Company's stockholders in the event of an unfair or coercive offer to acquire the Company. Management believes the Rights Agreement, however, should not affect any prospective offeror willing to make an offer at a fair price and otherwise in the best interests of the Company and its stockholders, as determined by the Board of Directors. Also, management believes the Rights Agreement should not interfere with any merger or other business combination approved by the Board of Directors.

Underwritten and Registered Direct Placement of Common Stock

        Effective May 6, 2014, the Company completed an underwritten public offering in which it sold 18.8 million shares of the Company's common stock at a price of $1.70 per share less underwriting discounts and commissions. The shares were allocated to a single institutional investor. The net proceeds to the Company from the sale of the Common Stock, after deducting fees and other offering expenses, were approximately $29.8 million.

        Effective March 5, 2012, the Company completed a registered direct placement in which it sold 22.6 million shares of the Company's common stock, par value $.001 per share, and warrants to purchase 22.6 million shares of common stock with an initial exercise price of $1.55 per share, at a price of $1.11 per unit (the "2012 Warrants"). Each unit consisted of one share of common stock and a warrant to purchase one share of common stock. The 2012 Warrants expired on October 31, 2013. In addition, the Company obtained the right to require investors in the offering to purchase up to an aggregate maximum of 19.0 million additional shares of common stock from the Company (the "Put Options") during two option exercise periods, the first such option exercise period beginning September 10, 2012 and the second such option exercise period beginning March 4, 2013. Each Put Option was subject to certain conditions which reduced the number of shares that could be sold or eliminate the Put Option. These conditions included a minimum volume-weighted average price (VWAP) and a minimum average trading volume of the Company's common shares during the 30 trading days prior to the exercise of the Put Option. The March 2012 sale resulted in net proceeds of approximately $23.1 million net of direct incremental costs of approximately $1.9 million.

        On September 18, 2012, the Company entered into an Investor Agreement with one of the investors in the 2012 registered direct offering pursuant to which the investor agreed to (i) waive the condition precedent to the Company's exercise of the Put Option requiring the arithmetic average of the average daily trading volumes during the measurement period set forth in the subscription agreement between the Company and the investor and on the exercise date be not less than 1.75 million shares and (ii) amend the subscription agreement to provide that the purchase price of the additional shares during the first exercise period would be discounted pursuant to a formula that resulted in a purchase price for the first exercise period of $0.94 per share. Additionally, pursuant to the Investor Agreement, the Company agreed to amend the exercise price of the 2012 Warrants originally issued to the Investor to $1.26. The exercise of the first Put Option resulted in net proceeds of $4.2 million. The 2012 Warrants still outstanding as of March 31, 2013 provided for the purchase of 22.6 million shares at a weighted average exercise price of $1.41 per share. On February 21, 2013, the Company entered into a letter agreement (each a "Letter Agreement" and, collectively, the "Letter Agreements") with each of the investors in the March 5, 2012 registered direct offering. Pursuant to the Letter Agreements, the parties evidenced their mutual agreement that the Company would not exercise any portion of the second Put Option. The Company chose not to exercise the second of the two Put Options because of its improved cash position and its desire to avoid stockholder dilution. On October 31, 2013, an unsolicited exercise of 2012 Warrants to purchase 4.7 million shares resulted in proceeds of approximately $6.0 million. Effective October 31, 2013, all remaining outstanding 2012 Warrants expired.

        The following table outlines the warrant activity: