Hang in Winlogon on Workstation Locked Dialog Box

A Windows NT computer may appear to stop responding (hang) in the Workstation Locked dialog box, but you will still be able to move the mouse and access the computer from the network.

This problem can occur when running a filter Gina.dll. This problem is caused 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 the Microsoft Knowledge Base:

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 in Winlogon if a custom Gina.dll's WlxLoggedOnSas function immediately returns with WLX_SAS_ACTION_LOCK_WKSTA.