Opening a folder containing a large number of AVI file can open quite slowly because the OS has to open each AVI file and extract info from AVIs. If you have a large collection, you can speedup XP's folder access to blocking it from automatically extracting this info. Doesn't hurt anything, the OS will read the info if you open the AVI.
Rename the key by placing a minus in front of the keyname to enhance file system speed when working with AVIs : change HKEY_CLASSES_ROOT\CLSID\{87D62D94-71B3-4b9a-9489-5FE6850DC73E} to -{87D62D94-71B3-4b9a-9489-5FE6850DC73E}. If it causes problems, remove the minus.
You have AVI files that you saved in Windows 9x and they have interference when opened in Windows XP. Fix :
Open Windows Movie Maker.
Click View
Click Options
Uncheck Automatically create clips
Import the movie file that has interference and drag it onto the timeline
Save the movie
During the re-rendering, the interference will be removed.