Prime error when vcore increased?

Hello,

I've overclocked my Q6600 to 3.2 (354.7x9), vCore at 1.3V, 4-4-4-12 ram 1:1 at 2V, I ran P95 last night for 3 hours with no error, so I decreased vCore by one increment (1.26something) and ran prime again, this time core 3 fails with a "rounding error, expected less than 0.4"

I increased vcore again, back to 1.3V, but this error is still persistant? (I've ran small FFT and Blends)

Why am I still getting this error?

Thanks!

System:

Q6600 G0 Stepping
Arctic Freezer 7 Pro Cooler
Asus P5Q-E
Patriot 4GB (2x2GB) Extreme Performance PC2-6400C4 800MHz DDR2 Dual Channel Kit
HIS Radeon HD5770 1GB GPU (Used to run 8800GTX until it broke, so this is the newest component)
Samsung F1 1TB HDD
Tagan 1000W PSU (cant remember model number)
Lian Li V1000 Case
Windows 7 Ultimate 64 Bit