At random intervals, regardless of if I'm working with the PC or just listening idly to music in iTunes, the system will hang for about 5 seconds at a time. During the freeze, both cores max out, the mouse and all apps freeze and the music will play the last half second of audio repeatedly until it fixes itself. Everything seems fine after the spike is gone. This will happen in 2 to 10 minute intervals. I'm confident it's not a virus as AVG isn't finding anything and I've only recently installed the OS.
The system is not overclocked and seems stable otherwise.
Windows 7 64-bit
4GB OCZ 1200 DDR2