DirectX application minimizes itself when it shouldn't
Not really game related, but since it's about DirectX, I think this is the best place. I have this application and at random times, it just minimizes itself. It still has focus but I see my desktop instead of the app which is fullscreen. There is no code that's executed that explaines any of this behavious, I get it when I just open the app and let it be and it still happens. I only get it on my desktop which is running windows xp professional sp 3, but I can't get it to happend on my laptop which I use for development and is running windows vista business sp 1. When it's about to happen on my desktop, I see that my cursor turns into one with an hourglass, and after it has been minimized, I can see in the performance log that on that moment, the cpu load was 100%, which isn't he case before and after the minimize. I don't know which process is causing this. My app doesn't contain any memory or resource leaks.
At this moment I'm testing some more and I seem to have come to the conclusion that it only minimizes itself after a few minutes if there is an explorer window open. When it's just my app (and taskmanager for all it matters) it doesn't appear to happen. It may be just a coincidence, but I have ran the app 2 times now with no explorer windows open for a longer amount of time then it usually takes before it minimizes, and it hasn't yet.
So I would like to know if anyone knows what is causing this, and more importantly how to fix it in other way then "close all explorer windows before starting the app".