In a Filmstrip Lister if the focus moves to a .mov file (produced with my digital camera), DOpus immediately crashes. This does not happen with other lister types.
What happens if you drop the same .mov file on Windows Media Player?
Nothing. A .mov file is Quicktime format. The Quicktime player opens and plays it successfully.
Quicktime plays in Media Player if it's set up right, and AFAIK if it isn't set up to play in MP then Opus shouldn't be playing it...
Let's experiment, though. Could you disable all the viewer plugins, as well as teh Shell Image Extraction option in Preferences, and then see if the crash still happens?
Shell Image Extraction was already off.
I turned off the Movie Viewer Plugin and the crashes stopped.
You've probably got a video codec (or splitter, etc.) installed that crashes on (some) QuickTime files.
Have you installed QuickTime Alternative or Nero? They're usually fine on their own but perhaps they're going wrong in combination with some other codec on your system.
If download GraphEdit and open the .mov file with it it should tell you which components are involved with decoding (or attempting to decode) the file. Unless GraphEdit crashes for the same reason that Opus does. 