Windows Movie Maker Problem

[ATAG_Dutch]

I'm hoping some of the more technically minded can help me out here.

My Windows Live movie maker will no longer show any avi clips. Black screen, sometimes with sound sometimes not.
This has only happened in the last couple of weeks and I've no idea why.

The raw Fraps avi clips play fine in media player, but movie maker will not show them. Still photographs show up ok though.

Consequently I can no longer make any CoD video clips.

No amount of Google searching has found a solution, and microsoft's forum is hopeless.

Anyone got any suggestions? I'm on Windows 7 home premium.

Thanks in advance.