I was feeling nostalgic and installed a vintage (pre XP) PC game on my computer. It required a very old version of QuickTime. I had no newer version of QT installed, so I let it install. Ever since, Media Center is not playing DVDs correctly. It's hard to describe. It plays too fast, but not consistently. It's as if it's skipping frames randomly. Less than double speed though. The game has since been uninstalled, but the problem persists. There was no explicit uninstaller for the associated QuickTime.
For the record, the DVD in question is one that we have played many times in MC without issue before. And I know that there is nothing wrong with the disc as it plays just fine in Windows Media Player.
In MC Options under DVD playback my video decoder options are Automatic, Nero Video decoder, or Nero DVD decoder. I've left it on automatic. I also tried reinstalling Nero to see if that would help, but it didn't.
I have also done an MC update (to 12.0.451) since uninstalling the game, but DVD playback is still hosed.