I can't exit Windows 3.11 normally. I have to use Control-Alt-Del twice. I always get the following error message "Progman.exe caused a general protection fault in module user.exe at 0001:40B6." Exit was working OK before.

Here is a section on tracking down and fixing General protection faults.

SYSTEMATICALLY ISOLATING GP FAULTS
==================================
http://micro.uoregon.edu/win31/gpf.html

Another page that deals specifically with finding the problem when user.exe is the cause;

http://www.md.huji.ac.il/hlpdsk/ntscp/gpf.html

Good luck