Oddly enough, this just occurred while testing your issue…
First I copied the three generic files, nothing. Renamed the level file, nothing, then the PGD, nothing… went to change the Level file name again and it started doing it, but got to Saving: blah blah(Collecting Garbage) and just froze.
Force-closed and checked the log to see that error. I’ve never had a crash from copying, moving or renaming files before until just then.
-WM