Screen freeze, unresponsive, no BSOD.

Hi. Lately I've had a couple of computer freezes. It happens randomly, sometimes there can be days between each freeze. When it happens, the screen freezes; the mouse is unresponsive but everything is still showing up on the screen. And if I have music on it stops and this high pitched sound starts playing. So no BSOD.... I End up having to do a hard reset or restart. I have no idea about...