If it's any help, I'm having a very similar issue without any luck. The only critical errors in event viewer are the kernel-power events, and there are no events of any kind noted within 10 minutes of the critical error. No BSOD, no restart, just a frozen machine. Happens under all sorts of conditions.
edit: It may be speaking too soon, but it looks like getting an update to the MSI BIOS stabilized the machine. Now that I say that, it's certain to fail, but so far, so good.