In Windows Media Player:
- Tools, Options, Performance, Advanced
- Turn everything in Video Acceleration off
Disable WMV Acceleration in your ATI video driver if it is on.
Reboot.
Install more current ATI Catalyst drivers (or re-install them).
http://www.ati.com
- Requires .NET Framework and Service Pack 2 be installed I think
Reboot.
Go back into Windows Media Player and turn each option in Video Accleration (as above) back on, one by one, and see if the problem comes back.
Also run Windows Update [
file://%SystemRoot%/system32/wupdmgr.exe] and check under Custom for any Media Player updates.
Also check at: http://www.microsoft.com/mediaplayer/ ; for updates.
I also had the exact same problem, you can disable overlays to fix it as a workaround, and/or try the above. (Overlays accelerate video playback, and you'll also get video deblocking, usually 3:2 or 5:4, thus with them on the video playback will look nicer).