when i get it its usually much worse than what you posted, but the same problem. not the overclock then... weird. never experienced it on stock kernel. i always assumed it to be instability as when i went to a higher default voltage profile i didnt experience it. Did it still do it after reboot? I find when i did occur that the phone would be very slow and churn away until i rebooted. Is it just the graphics you have the problem with?