well, in my opinion if after 2 week the problem is still the way of overclocking i suggest you again to bring the computer to a computer shop where it will be checked and overclocked properly... :sm103:
What are your temp reading with realtemp? It could be an overheating issue as well. YOu made no mention of what you're using for cooling but if the fan and sink use pushpins I'd be real tempted to make certain its still properly seated. If it were an OC failure the board would normally reset to default settings if the OC isn't sticking. Download realtemp from http://www.techpowerup.com/downloads/1872/Real_Temp_3.60.html and post the screenshot of the results.