I got the (stupid...) idea to boot my old win98 system I had on a separate drive. I disconnected the precious knoppmyth drive and put it aside. After my business in win98 was finished I switched the drives again and booted knoppmyth. However something weird has happened. My resolution is weird (overscanned) and I have severe audio sync problems in mplayer when playing a file I had no problems with whatsoever. When I look in XFree86.0.log I see it runs in 952x518 which is the setting I normally use with my projector (native res is 960x540). However the screen is now very overscanned vertically.

Any ideas as to what may cause this?

OK so I figured out part of the problem. From the XFree86 logfile I learned the virtual desktop had been scaled to 952x600. Don't ask me why. I then edited the XF86config_4 file and removed all resolutions exept the one I wanted and it did the trick. The audio issue must somehow be unrelated. I've been looking to get a new card anyway since I need one that can output 5.1 so I might as well do that now. No reason to fight for a lost cause so to speak.