BUG: VDM Apps Can Cause Other Applications to Redraw Slowly

• Microsoft Windows NT Workstation version 3.51
• Microsoft Windows NT Server version 3.51

SYMPTOMS

On WinNT 3.51, moving a VDM Application on the screen or changing its focus in relation to other 16-bit or 32-bit Windows-based applications (moving to the foreground or background) causes the Windows-based applications to redraw slowly taking four to six seconds.

CAUSE

Some VDM applications, such as Microsoft QuickBasic applications or Edit.com with the menu pulled down, have a thread that loops tightly while waiting for keyboard input. This thread, always being in the run/ready state, slows the redraw of other Windows-based applications.

WORKAROUND

This problem can be eliminated by creating a .pif file for the VDM Application using Pifedit.exe. Click the Advanced button, and reduce its Foreground and Background Priority by half.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.