Overview Every time I started a new explorer, explorer crashed. According to the error in the event logs it looked like ffdshow was causing the crash.
Download ShellExView and disabled all the extensions that were not Microsoft to see if one of these extensions were causing the crash. Didn't change anything.
I realized ffdshow was probably crashing because it was trying to open something (video file) it did not like (corrupt?). I'd been playing a lot with codec's recently to get an AVI file out of ScanStation mov files and this probably initiated the issue. The "Quick access" folder had a file(s) in it that was causing the crash.
Search for Explorer options. Clear "Quick Access" history.