The compatibility tab was introduced in Movie Maker version 2.1 to help solve problems with coded compatibility. You can turn off any or all of the codec's listed in the tab section. It's best to turn them off one at a time and test to see if the problem has been cured.
With Movie Maker open, go to
Tools
Options
Compatibility
You will now see a list of codec's or filters as MM calls them with check boxes ticked. Click on a check box to untick the codec and then test movie maker.
