Pressing CTRL+ALT+DEL When Logging On Can Cause Blue Screen

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0

SYMPTOMS

If Client Services for NetWare (CSNW) is installed and a user presses the CTRL+ALT+DEL key sequence immediately after entering his or her password at the logon prompt, the system halts with a C000021A STOP code.

CAUSE

It is by design within Windows NT that, if the Secure Attention Sequence (SAS) (CTRL+ALT+DEL) is pressed, any logon scripts currently running are terminated. This gives the user the ability to easily kill any logon scripts that may have stopped responding. However, if this sequence is pressed before a process running a logon script has started running properly, a blue screen STOP error can result. This error is caused because Winlogon.exe performs an access violation.

NOTE: The user does not have to have a logon script defined for this problem to occur. With CSNW, the logon script processor is responsible for checking to see if a logon script is actually available to run and, therefore, is started even if no script is defined.

RESOLUTION

There is a fix available from Microsoft Technical Support that fixes this problem.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Keywords : kbbug4.00 kbfix4.00 kbfix4.00.sp3 NTSrvWkst
Version : 4.0
Platform : winnt
Issue type : kbbug