Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Operating activities
Net loss	$ (12,288)	$ (20,126)	$ (32,061)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,451	2,950	2,853
Amortization	881	1,215	1,327
Stock-based compensation expense	1,605	1,462	1,499
Impairment of assets	250	6,023	12,130
Loss (gain) on sale of property and equipment	1	40	(21)
Provision for inventory reserves	2,212	509	361
Provision for bad debts	132	575	285
Other	177	258	265
Changes in operating assets and liabilities:
Accounts receivable, current and long-term	1,687	7,116	(1,909)
Inventories, current	1,220	(3,249)	(2,356)
Deferred contract costs	(899)	137	651
Prepaid expenses and other current assets	2,084	(2,645)	1,261
Accounts payable	(81)	713	2,475
Accrued expenses and other	(635)	1,803	838
Deferred revenue, current and long-term	300	(254)	(410)
Net cash used in operating activities	(1,903)	(3,473)	(12,812)
Investing activities
Purchase of property and equipment	(660)	(401)	(2,006)
Purchase of short-term investments	0	0	(2)
Sale of short-term investments	0	0	472
Additions to patents and licenses	(291)	(6)	(234)
Proceeds from sales of property, plant and equipment	2,600	35	1,040
Net cash provided by (used in) investing activities	1,649	(372)	(730)
Financing activities
Payment of long-term debt	(880)	(1,901)	(4,494)
Proceeds from revolving credit facility	87,935	65,767	2,500
Repayments of revolving credit facility	(85,025)	(64,549)	0
Proceeds from long-term debt	0	0	446
Proceeds from repayment of shareholder notes	0	0	46
Proceeds from issuance of common stock, net of issuance costs	0	(2)	17,465
Payments to settle employee tax withholdings on stock-based compensation	(19)	(34)	(22)
Deferred financing costs	0	0	(406)
Net proceeds from employee equity exercises	8	104	441
Net cash provided by (used in) financing activities	2,019	(615)	15,976
Net increase (decrease) in cash and cash equivalents	1,765	(4,460)	2,434
Cash and cash equivalents at beginning of period	15,542	20,002	17,568
Cash and cash equivalents at end of period	17,307	15,542	20,002
Supplemental cash flow information:
Cash paid for interest	164	191	287
Cash (received) paid for income taxes	(153)	18	42
Supplemental disclosure of non-cash investing and financing activities:
Vendor financed capital lease addition	$ 175	$ 396	$ 0