Seriously, though, the best advice has been given. Trash preferences (see DUC forum, Mac PTHD, top link for a quick application) and retry. That fixes most things and it only takes a few seconds to put prefs back in.
If that fails, reinstall (what a 20 min job?). You don't have to do plugins, etc, just PT.
In the time you've taken to b & w on this thread about no responders, you could be working again.
These things crop up all the time whether with Digi's own hardware, LTHD cards, X HD cards, SSL DeltaLinks, etc. Always the same solution... Rarely is it a hardware problem if no one's been knocking things around in the machine room.