Media Center cannot find videos in My Videos

I have a weird problem. A day ago, the Media Center was able to detect all my
videos (.avi and others). Now, suddenly no videos are detected when I click
on 'My Videos'. Even the sample videos that came with the Media Center can't
be found. However, those videos CAN be played on windows media player 11
which is installed on the computer. When i try to run it on media center,
nothing happens, the media center just opens and the video is not played.
Even more suprisingly, when I put my mouse over 'My Videos', some of the
recently-viewed videos can be seen and can be played (in the Media Center).
What could be the problem as to why videos cannot be found now?
Thank you very much if u could find a solution!

 

I am having the same problem with all items that should be in the library for
a few days now.

I tried readding the folders to media player to scan, and it doesn't do
anything. Even if I drag in new files, they will play fine, but they will
not add to the library. It's quite frustrating as I like the library
functionality better than making play lists.

The odd thing is that my xbox360 still functions normally, with the
libraries working properly. However media centre and media player do not.

 

I had the problem and it was caused by "losing" the registry entries for .mpg
etc. I think this was caused by uninstalling Nero. However the fix is to
export the registry keys fro another computer and reapply them to the
registry. To check, run regedit and see if an entry exists on the following
path:
HKEY_CLASSES_ROOT and look for a .mpg key.