Did you try it on a good desktop? I've seen laptops screw up like this but there's not much about the PC here.
Bob
Hello, I'm new here but I really need help with my Sony vegas Pro 12. (Maybe owners with other video editing software work too)
I don't know if this problem was there when I first got my Sony Vegas because I didn't use it often at that moment. And also because 'the problem' sometimes takes longer to appear. (This varies from 30 seconds to 10 minutes).
When I open or start a project and start to put clips in/edit them, there is no problem. But when I start to play the video, the frames (or the clip itself, I don't know) start to mess up and will get worse after time. When this happens I have to restart my Sony Vegas to solve this, but after a while the problem comes back. Sometimes I have to restart my Sony Vegas more than 5 times just to see how my project looks so far.
Also during and after rendering the video the frames mess up. It took 6 tries to render a 5-10 second video because of it. Normally I make videos of atleast 3 minutes so rendering would take a long time.
This means I will never be able to render my videos because of this problem. Could this mean that I need a graphics card (and if I do, why did this problem never occur on my Sony vegas pro 9? ) or can't Sony Vegas take my clips? Please help!
Extra information:
1. I've had Sony Vegas Pro 9 on this computer before my hard drive stopped working (I bought the exact same hard drive after that so it should be the same computer). And on Sony Vegas pro 9 I never had this problem.
2. The clips mess up with AND without effects on them.
3. I've tried changing the quality in the rendering settings and also the preview quality.
4. I've tried multiple clips from different cameras.
5. After one clip starts to mess up, all the clips will mess up even when I put new ones in. Here is a picture of how the clips mess up most of the time. http://prntscr.com/16ncvh on 1: the screen goes completely black. On 2: It looks like the screen crashes. On 3: A random clip shows up on the screen during playing a different clip.
6. Almost all the clips are .avi files, but sometimes I use .wmv files too. (However, this problem never occurred on my Sony Vegas Pro 9)
7. This is my screen shot of the information about my CPU etc. http://prntscr.com/16qqt7
(I have one hard drive)

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic