UPDATE: I was wrong, the fix is not included in the Windows Media Center update and you have to download the fix directly from Microsoft, if your experiencing the problem you can get the hotfix from Microsoft x86 or x64
Today I wrote about the update for Windows Media Center that fixes a number of issues but I thought it would be worth highlighting one of the fixes as Media Center developer Olcay Buyan points out on this blog. The patch KB978632 fixed a issue that can cause 3rd party Media Center apps to crash when they try and interact with a tuner
Microsoft finally released a hotfix for a bug that affects Media Center extensibility applications that are using tuners. The addressed bug freezes the extensibility application, the host (ehexthost.exe) and the Media Center (ehshell.exe), when applications request a tuner while no tuner is available and the user clicks “Cancel” on the conflict page that appears. Closing Media Center doesn’t help, you need to kill ehshell.exe and ehexthost.exe in your TaskManager to use Media Center again
Developers have been complaining about this problem for some time so its good to see the bug addressed
via Olcay Buyan