Quick post.
If like me your Explorer crashes when opening a folder with video files, it s probably because you installed some dodgey software which is taking over the default explorer thumbnail generator.

To restore it, open the registry editor (type regedit in the command line)

find the following key

HKEY_CLASSES_ROOT\SystemFileAssociations\.avi\shellex\PropertyHandler

and delete whatever value you have for the “Default” key. Press Ok restart and off you go!

Thanks google and Annoyances.org website.