This article was previously published under Q189291
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A Windows NT computer may appear to stop responding (hang) in theWorkstation Locked dialog box, but you will still be able to move the mouseand access the computer from the network.
This problem can occur when running a filter Gina.dll. This problem iscaused by a race condition in Winlogon wherein Secure Attention Sequence(SAS) messages are disabled and not reenabled.
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.
A race condition resulting in a computer that quits responding exists inWinlogon if a custom Gina.dll's WlxLoggedOnSas function immediately returnswith WLX_SAS_ACTION_LOCK_WKSTA.