Windows 7: Memtest runs then boots to windows

I've been attempting to run Memtest for the last few nights, attempting to let it run for nine hours each time. Unfortunately when I wake up and come to check the status I find that the computer has booted to windows and been sitting at the login screen for an unknown period of time.



Does this mean that memtest is crashing or finding an error? I can't imagine that if it finds an error it would boot to windows since that would make it a bit worthless.

If it helps anythings I'm trying to solve a Kernel Power 41 lock up issue

Thanks!