ffdshow is a mpeg-4 video encoder/decoder. Are you trying to watch a video or something. DivX and XVid use it. You can try installing the newest version of ffdshow or if you have an older divX player, try upgrading it to the newest version.
This is probably caused by the Xvid or ffdshow!~video filter. Explorer crashes because the Xvid video filter has encountered a problem while generating the thumbnails for your Xvid-encoded video files.