For some reason, I can't run any game using hardware acceleration. For example in Midtown Madness 2, first this game gave me an option of choosing either "Software acceleration" or "Hardware acceleration" but now it's only showing "Software acceleration" in the list. I have tried updating Directx and also my video card driver but it still can't run in hardware acceleration.
The reason why I am mentioned this is because any Directx or OpenGL demo I run is also very slow in speed (it was used to be fast before).
This problem has randomly occurred in the past too but I had to always reinstall my operating system in order to get my real settings back.