[musicman691]

As I understand it: existing session - crash. New session with import from old session - crash. No crashing on other sessions right?

Do you get crashes if you reboot after a crash?

A couple of oddball things come to mind and they may not be it but worth looking into. First is have you cleaned out the dust bunnies from inside the Mini? Take off the bottom cover and clean out the little blower intake and exit - Mini's get their air intake through the bottom cover. My thinking here is overheating. The other is is your ram okay? I don't know how to really test the ram so can't help there.

Speaking of ram - I wonder if you may have a program with a memory leak? Also not all programs return unused ram when they quit.