You're welcome "Git",
You may also try goosing the metadata (e.g. change the comments field) - dunno if it would work, but may be enough to force Windows to check and recreate thumb. Or make a batch file that does nothing but "touch" the file (make no real changes, but fool Windows into thinking there was a change), then you could just drag files with wonky thumbs onto the batch file... Actually, there are free touch utilities (e.g. FileTouch.exe) so you don't have to make a batch file.
Although I consider it a bug in Windows, it does beg the question of whether Lr could do something differently to keep it from happening - maybe write to a temp file, then rename, instead of writing direct to the destination filename (or does it already do that?). I've never seen it happen via any other app. Have you?
Rob
