I think I've stepped into the twilight zone today. I'm running XP with the latest service packs and updates in a VM. It contains two administrative user accounts both without passwords. I log in as User 1 and start my Win32/C++ application. The window appears and all is well with the world. I then log off without first closing my app. Yes, I used "log off" not "switch user"
I then log in as User 2 and my application is still running and I see it on the User 2 desktop. I can even interact with it - it appears to be functioning normally. And task manager shows it running as User 1.
Any ideas which might be going on here? Other applications (like notepad) don't exhibit this issue, yet mine does. Seems to me I'm doing something wrong in my code, but it really is a rather standard win32/c++ app. Perhaps I'm not processing some shutdown message properly? I'm sorry I can't give more specifics right now. I'm really hoping for some clue to spark further research.