I actually figured out the problem. I have a plantronics DSP-500 headset which runs off usb. I patched my usbport.sys driver for 500 Hz mouse report rate. I didn't restart my system for about a week, totally forgot about it. Reboot my system, and I notice every application is hanging and the system BSODs out. Very strange, figured it would be related to my overclock. So I restore the system to bone stock settings, still crashing. I tried to restore system files with sfc /scannow but the process yielded no change (guess it doesn't index usbport.sys in the 50 megabyte default).
I think safemode was stable because it doesn't load audio drivers. I guess that should have been a big indication it was a driver issue (bangs head). Could have saved myself a bit of time there...
The reason I even figured out what the problem was is because I patched the usbport driver again on the fresh system and then I got all the same symptoms unless I unplugged the headset. Fortunately, the patcher makes it straight forward to restore the original version of usbport.sys so it wasn't really a big deal what I reckognized what the problem was. Moral of the story!: Don't forget to reboot... or perhaps, don't buy plantronics headsets. I guess patching the usb system driver isn't the best method for increasing mouse report rate, I wonder how the copperhead drivers do it?