Recently my computer crashed and came up with a error saying : DPT_WATCHDOG_VIOLATION.
I restarted it after it said it would restart, because i left it for an hour and nothing happened. When I was on my windows 8 computer I checked the drivers in device manager and found a yellow exclamation mark on a unknown device. I searched it online and said the driver was not installed propably. This was probably caused after reinstalling windows 8 on my computer : http://www.bleepingcomputer.com/forums/t/579755/cortana-and-start-menu-broken/