Occasionally Windows Media Center can corrupt its recording schedule files which can lead to Media Center not recording TV shows or downloading guide data

For example:
Media Center had tries to record the same program 6 times, and reports a conflict in the event log
e.g.
F1: Belgian Grand Prix Qualifying Highlights was not recorded because the program was pre-empted by the broadcaster. According to the Program Guide F1: Belgian Grand Prix Qualifying aired instead at 09/15/2007 12:30:00 on channel 28

To repair the system:

1.  Right click on "Computer" and select "Manage".

2.  Open up the services and get ready to temporarily shut down the "Windows Media Center Scheduler Service" and "Windows Media Center Receiver Service".

3.  Open up the following directory "C:\ProgramData\Microsoft\eHome\Recording".

4.  Shut down both of the Media Center services in #2 above and rename (or delete) the "Recording.xml" and "Recording.xml.bak" 

5.  Start the service "Windows Media Center Service Launcher" (this will start both of the other services correctly).

You will have to reschedule your TV recordings