SetTimer() API Causes Memory Leak in the WOW Subsystem

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This article was previously published under Q159971

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SYMPTOMS

When you run 16-bit applications, such as Microsoft Project 4.0, Microsoft Mail 3.0, or Schedule+ 1.0, which frequently call the SetTimer() API, the system may run out of memory resulting in poor performance and very sluggish response.

The following error message may also appear:

System Process - Out of Virtual Memory

Your system is running low on virtual memory. Please close some applications. You can then start the System option in the Control Panel and choose the Virtual Machine button to create an additional page file or to increase the size of your current paging file.

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CAUSE

The SetTimer API causes a memory leak in the Windows on Windows (WOW) subsystem. A memory leak is caused by an application or process that allocates memory for use, but does not later free it up when done. The result is that available memory is completely used up over time, often causing the system to stop functioning properly.

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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

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