Access Violation Causes 16-Bit Applications to Silently Quit

• Microsoft Windows NT Workstation versions 3.5, 3.51, and 4.0
• Microsoft Windows NT Server versions 3.5, 3.51, and 4.0

SYMPTOMS

16-bit applications, both DOS and Windows based, run successfully for a period of time and then quit without cause.

RESOLUTION

Verify that VIF and VIP are not turned on at the same time. This problem can be avoided by disabling the Pentium Virtual Machine Extensions (VME) because VIF and VIP are only used by VME support. To disable the use of VME in Windows NT, add the following value to the registry:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use Registry Editor at your own risk.

1. Start Registry Editor (Regedt32.exe) and go to the following subkey:

         HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Wow
   

2. On the Edit menu, click Add Value. Enter the following:

         Value Name: DisableVme
         Data Type: REG_SZ
   

        (hit OK here)
   

         Data: 1
   

3. Click OK, and then quit Registry Editor.

4. Shutdown and restart you computer.

MORE INFORMATION

If you run the application under a debugger such as Ntsd.exe, the application will break to the debugger instead of quitting. The debugger shows that the VDM caused an access violation after carrying out an STI instruction (this indicates that the program currently running does not have high enough privilege to enable hardware interrupts).

NTSD: access violation eax=00010240 ebx=0000000a ecx=00004000 edx=00000010 esi=0001573c edi=0000000a eip=000053e0 esp=0000079c ebp=000bea74 iopl=0 vip vif nv up ei pl nz na ponc cs=fe2e ss=00a7 ds=0040 es=0000 fs=0000 gs=0000 efl=001b0206

fe2e:53e0 ebf8            jmp    53da

0:000> u fe2e:53e0-1

fe2e:53df fb              sti
fe2e:53e0 ebf8            jmp     53da