Fullscreen lag?

I've been experiencing freezes/major lag in videos (youtube, veoh, etc) in full screen...I click full screen, and every couple of minutes, the video freezes while the sound is still playing.

Could this be due to an OCing error? ie. not enough voltage in RAM, not having the RAM timed to the CPU, etc

Or is this a GPU error?
It is mostly HD based. Although I've experienced lag on non-HD as well, as well as veoh videos.

The computer I'm using has a E6300 (1.86GHz) stock OCed to 2.2GHz.

I've recently lowered it to 2.1 to see if it makes a difference