My brother Has windows 8 pro with a SSD, 2 monitors and a GTX-570. He has 16GB of RAM and a ASRock motherboard. All of these parts are less than 12 months old.

At random intervals both of the screens will simultaneously go into standby and the computer appears to freeze (music playing will continue for a few seconds then stop).

He has to power off the computer, then back on again to get it to work.

Memtest had no errors, and there was nothing obvious in the event logs.

Any ideas on what might be causing the problem?