Parallels 7. I upgraded OS X today and it forced a reboot, this got cancelled by Parallels which would not quit. It was trying to suspend a Centos 6 VM which was minimised in the dock and which was stuck at '9' on the countdown. I had to force quit and the VM restore image was corrupted on restarting Parallels after the reboot/system upgrade. This isn't easily reproducible but ...
