Not sure if this will solve your problem, but try to make sure none of your gear is sending midi signals when you boot (preferably turn it all off) I've had this problem before on a powermac with serial midiman interface (I though USB would have fixed that tho) I'd be holding down a key or twisting some knob (as you do when you're waiting) and I would get a bus error and crash. So restart after turning off virtual memory and make sure everything is off.
hope that helps
-m