Puzzling problem with WMP Video Controls

Archived from groups: microsoft.public.windowsxp.video (More info?)

Can anyone help with a problem I'm experiencing with
Windows Media Player 9. I am unable to adjust the video
settings (brightness, contrast, etc.) when playing a
video. When I try to, the sliders instantly revert to
their default position. This problem is new - prior to
today I could adjust those settings during playback. The
problem occurs even with some avi files that are windows
video formats, and with which I was able to adjust the
sttings before. Some videos still allow adjustments, but
others that previously did do not. Has anyone experienced
this problem? Any guidance or ideas would be
appreciated! I have reinstalled my video drivers and
direct-x but still the problem remains!
jeff