I am using an official trial version of Premiere Pro CS6 as part of Creative Cloud. I am editing on my MacBook Pro 17" (newest model) with h.264 footage recorded on my Canon 550D.
Everything works fine, imports and edits like a dream. However, during editing, if I simply go to Project -> Project Settings -> General - then don't even change anything, just ok out of the dialog box then it crashes.
When I say crashes, the video disappears and I cannot do anything at all until I exit out and reboot. No messages appear until I do a 'force quit' and then I get the standard "A serious error has occurred" etc.
Of course the obvious solution is to not select Project Settings when editing! Which I will do for now, but I would like to think that I can change any settings I like without it crashing every time!
On reading the advice on a separate thread I updated OSX from 10.7.3 to 10.7.4 which seems to have fixed the problem. Probably should have checked that first!