Computer completely froze (OC'ing)

[Nechen]

Ok so I OC'd my E6400 C2D to about 2.6 333Mhz internal clock x 8 and everything ran great for a few days. All the sudden I was playing Garry's Mod on Half-Life 2 and everything completely froze, nothing was responding including my keyboard (when I would press the numlock key none of the lights would change in response)

After I restarted my comp I panicked and just reset to optimized defaults in BIOS back to 2.13 267Mhz internal x 8 and then my keyboard and mouse weren't coming back on. I use a Saitek Keyboard and a Razer Diamondback 1600dpi mouse. After a couple restarts it finally said "Found new hardware" and everything came back online.

I've not had any problems since but I also am running all speeds at stock right now for fear of crashing again. Anyone know if my OC'ing caused this or could it be something related to a USB problem? I downloaded some Windows Update to the USB drivers or something to that extent.

Any ideas or comments?

Thanks.