Help! big performance drop, don't know why!

I built this conroe e6400 system about a couple weeks ago and it was working fine until this morning. For no reason I can fathom, the performance just fell by two thirds! I ran 3dmark06 and it scored 2,210, whereas yesterday it scored well over 8,000! Performance like that dropped for all games. How do I test the CPU to rule it out? What benchmarks can I use and what scores should I expect? How can I isolate the cause? I didn't do anything to the computer in the time it took the performance hit! I changed no settings at all.

Here is my system specs:
e6400 OC'd to 2.84 Ghz
Crucial tenth anniversary, 2 gigs (not overclocked)
eVGA 680i motherboard
XFX 8800 GTS video card (not overclocked [yet])
E-MU 1820 sound card
windows XP pro, sp2
all drivers are the latest.

Please, someone help!

nevermind, solved...

i uninstalled the graphics drivers and reinstalled them, that did the trick. I just wish I knew what caused the problem in the first place....

Well it was eather corrupt or the first time you ran the Bench you had the settings on proformance and the second time you might have had it on quality