What do you mean by disabling file types?
Have you tried using ShellExView to look at which shell extensions are installed?
Are you working with video files? There could be a video codec crashing, even with the movie plugin disabled, if thumbnail generation is being triggered. (If it is that, you might also see some kind of crash when pointing Explorer's thumbnail view at the same files.)
Are any crash dumps created, matching the date/time of the crashes?