Dynamically Loading/Unloading WINRUI32.DLL Causes System Hang

• Microsoft SNA Server versions 2.0, 2.1, and 2.11

SYMPTOMS

When you dynamically load and unload the WINRUI32.DLL, your computer hangs. This symptom occurs sporadically.

CAUSE

This problem occurs during a call to FreeLibrary (hLibModule) where hLibModule was previously set to the result of a call to LoadLibrary (WINRUI32.DLL).

The hang occurs when the WINRUI32.DLL is unloaded by the FreeLibrary()call. The hang is caused by WINRUI32.DLL trying to remove its DMOD routing procedure during DLL detach processing. There are certain procedures that cannot be reliable performed inside detach processing, for example, waiting for something like the DMOD routing proc table to become available.

Existing applications that do not call WinRUIStartup/WinRUICleanup continue to function as before.

RESOLUTION

Microsoft has updated the file LIBS\WIN32WINRUI32.DLL to correct this problem.

The fix to the WINRUI32.DLL removes the RUI routing procedure during the processing of the WinRUICleanup() call and ensures that the DLL detach processing does not attempt to do it again. To properly load and unload the DLL you need to always call WinRUIStartup before your first RUI verb and WinRUICleanup before freeing the WINRUI32.DLL.

STATUS

Microsoft has confirmed this to be a problem in SNA Server for Windows NT. This problem was corrected in the latest SNA Server for Windows NT, 2.11 U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

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