Go to control panel, display, settings, advanced and turn the performance way down to see if your video card may have something to do with this.
I found it caused freeze ups on my system.
I got a new invidia? card and it installed some new DLL's in windows/system to make things more stable and since then I have had no problems! I don't know what it installed but I have never had things this good, ever! It was $25 and well worth it!
Just a suggestion.