Are you running Windows XP Media Center Edition 2005?
When you watch some videos, do they play the video in fast-forward while the audio plays at a normal rate of speed?
When you navigate the UI while or after playing a video, does the Media Center UI crash on you, forcing you go get up off of your recliner, find the mouse and actually click on the "Send Error Report" button before you can sit back down and hit the green button again to soothe your need for MCE love?
Well, that has been happening for me A LOT. Turns out that the version of the DivX codec I had installed on my Media Center PC had compatibility issues with the Media Center app.
So, here's what to do:
1. Close the Media Center application, Media Player and any Explorer Windows.
2. Go into "Add/Remove Programs" and uninstall all of your old DivX codecs.
3. Go to http://www.divx.com and download DivX 5.21.
4. Install DivX 5.21.
5. Go into the Decoder Configuration Utility in the DivX program group, flip to the second tab and put a check next to "Disable logo."
6. Hit the green button and test the fix.
It worked quite nicely for me.