Sony Vegas 11 Dead Frame Issue

For my current editing software I use Sony Vegas Pro 11. It was working without any hiccups for a very long time but then it decided to make dead frames in my video clips if I choose to have two clips playing at the exact same time.

This is limiting me from making videos for my channel because it's that bad of a problem. I know for sure that it's not my rig that's the problem or my HD PVR 2 Gaming Edition. Here's a screenshot of what happens when I try and overlay clips on top of each other. All help is appreciated.