I posted this elsewhere, but you can blow away the database and fix these issues using the following steps.
1. Close the Media Center UI/Shell (ehshell.exe)
2. Open an Administrator Command Prompt (launch Command Prompt with ‘run as Administrator’ option).
3. In the Command prompt - Change to the root ‘ehome’ directory (ie. c:\windows\ehome)
4. Run the mcupdate.exe command with the parameter ‘-MediaCenterRecoveryTask’
Ie. mcupdate.exe -MediaCenterRecoveryTask
5. Start the Media Center UI – and reconfigure your Media Center system.