CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (4,978)	$ (6,189)	$ 3,846
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Allowance for sales returns, doubtful accounts and other	(8)	(5)	16
Provision for excess and obsolete inventories	1,067	2,079	777
Depreciation and amortization	1,633	1,981	2,375
Stock-based compensation.	2,077	2,228	2,278
Deferred income taxes		1,224	(127)
Windfall tax benefits from stock options exercised		33	(92)
Amortization of bond premium on investments	593	842	1,015
Changes in assets and liabilities:
Accounts receivable	(11)	2,008	322
Inventory	(1,294)	3,545	2,139
Prepaid expenses and other assets	2,854	1,046	2,523
Accounts payable	(1,915)	1,066	(1,607)
Accrued expenses and other liabilities	811	(857)	839
Deferred revenue	292	(554)	407
Net cash provided by operating activities	1,121	8,447	14,711
Cash flows from investing activities:
Purchase of investments	(16,009)	(35,866)	(35,609)
Sales and maturities of short-term investments	39,699	28,412	33,446
Purchases of property and equipment	(481)	(761)	(385)
Net cash provided by (used in) investing activities	23,209	(8,215)	(2,548)
Cash flows from financing activities:
Repurchase of common stock	(30,026)	(2,880)	(3,626)
Windfall tax benefits from stock options exercised		(33)	92
Proceeds from issuance of common stock under employee stock plans	952	3,081	857
Net cash provided by (used in) financing activities	(29,074)	168	(2,677)
Net increase in cash and cash equivalents	(4,744)	400	9,486
Cash and cash equivalents at beginning of the year	41,520	41,120	31,634
Cash and cash equivalents at end of the period	36,776	41,520	41,120
Non-cash financing activities:
Purchases of property and equipment through accounts payable and accruals	6		51
Supplemental cash flow information:
Net cash paid (received) for income taxes	$ (2,394)	$ 2	$ (2,253)