Trying to figure out how to debug a Media Center add-in? See details on how to do it at the Media Center Platform Team blog at http://blog.mediacentersandbox.com/DebuggingAddinAssembliesInWindowsMediaCenter.aspx and to get symbols see http://blog.mediacentersandbox.com/HowToDebugARunningWindowsMediaCenterApplicationInWindowsVistaUsingVisualStudio2005.aspx

The quick summary: to get more details add
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Media Center\Settings\Extensibility]
EnableErrorDetails = 1 (REG_DWORD)

To be able to attach a debugger:
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Media Center\Settings\Extensibility]
EnableAddInLaunchDebugging = 1 (REG_DWORD)

Thanks Media Center team!