Audition crashing when deleting/shorten silences?

That's a hang - it's just waiting for something, rather than it's failed for whatever reason. A crash will either make Audition just disappear, or put up a message saying that it's going to close and you won't have any choice about it. There is supposedly a 'hang' investigation going on at present - not sure at all what may or may not be behind that yet. If you look in the Help menu, you'll find a route to the log files, and it might be worth cutting and pasting a recent one from a session where this has happend, just to see if there's anything obvious, but generally hangs don't reveal a lot...