Could you generate some more process snapshots and send them to us? It's possible the one snapshot we have isn't indicative of where the problem is, or is sending us down the wrong path. Making 5 or so is best, and if you compress them with 7z solid compression, the archive should still be fairly small.
A Process Monitor log of what happens when the context menu goes wrong may also reveal some details. (Only one of those is needed. If you generate one, please let us know which file/path was right-clicked, so we know what to look for.)