Even if your PC running Microsoft Media Center Edition was fully patched for the daylight savings time change, there is a problem effecting many people where shows that were scheduled to be recorded did not correctly change their record start and stop times.
Thus many people, including myself, have had shows missed. I’m quite cheesed that I missed the latest Battlestar Galactica!
The fix, as discovered by someone over the www.thegreenbutton.com is to go into your channel configuration, deselect all but one channel (that you’ve never recorded anything from), click save, wait for the CPU to go back to idle, then go back into the channel configuration, reselect all the channels (or at least those that you watch), and save again.
At that point, all times for all recordings should be fixed.