Computer stops in the middle of boot at random; no BSOD.

Hi,

Recently, my computer have begun crashing at random during boot, leaving me with a black screen and a silent harddisk. When rebooted, the computer boots normally.
Today, I got an even more curious error; the screen split into 16 or 20 loading screens with white, horizontal stripes every 2 centimeters or so.

I have run CHKDSK earlier without luck, and can't run it at the moment because I'm on battery.

Any clues?

Best regards,
Anders

Nvm, seems like it's a problem with an Nvidia update.