As I described in this blog post, we found an issue with a Windows Media Player hotfix (KB910393) if it is installed after KB908250 for Media Center 2005 and there is not a reboot in between them. We have heard from a lot of people impacted by this issue ever since KB910393 went live on Windows Update (which happened on Tuesday, November 29). So we have decided to temporarily remove KB910393 from Windows Update while we weigh our options and figure out the best possible fix. If you visit Windows Update on a Media Center 2005 computer with Update Rollup 2 installed, you should not see KB910393 offered as a critical update as of some time earlier this afternoon.
If you have already run into this interaction issue, you can use the workaround I listed in this blog post. There is no need for you to uninstall KB910393 if you already have it installed.