That error means your overclock or memory is not stable.
Make sure your overclock is not pushing the memory over its limits(most time memory over blue screens). Check in the bios under MIT to see the memory speed or use CPU-Z
Notch up the cpu voltage a small bit, Try 1.250 and do not go over 1.4(1.5 with good cooling)if you want it to last long. Many user go farther, but IMO thats the safe limmits for me.
Once you get stable try dropping the voltage one notch at a time until the system can run prime for at least 12 hours(24 recommended).
Download CPU-Z. Do not worry if you see a slower speed and a multi of 6. That is part of intel's power saving options.http://www.cpuid.com/