Major rendering problem with Sony Vegas 9?

This is a pretty weird problem that I can't get my head around. I recently did a Let's Play on my computer, but for some reason the file was split into 11 parts. That's not really a problem because I could just put them together in a video editor. So I tried out Sony Vegas 11 first. No matter what I tried rendering my 13 minute video as, it would have a constant green-flickering, and when there was no flicker the frame rate was horrible. Needless to say I gave up on Vegas 11.

So now here's my problem with Vegas 9. I rendered one small part of my video to make sure it worked, and it came out perfectly. So then I go and try to render the whole 13 minute thing, but no matter what I try I get this error. "System is low on memory. You may be able to reduce memory usage by closing other applications." Now, look at my specs below and tell me if that should be happening. It shouldn't, which confuses me. It renders perfectly on my friends PC with 2GB of ram (and his ram is lower quality than the 4GB I have). Could anyone tell me what's wrong?

Windows 7 Home Premium 64-bit (6.1, Build 7601)
Intel Core i5 CPU 760 @ 2.80GHz (4 CPUs), ~2.8GHz
4GB RAM
Page file: 2223MB used, 5962MB available
DirectX 11
ATI Radeon HD 5830

Try this app,
VirtualDub download (at SourceForge) - virtualdub.org

You can load the first clip and then append the rest of them.
then in the Video Button on the Menu, select "Direct Stream Copy", and check the Audio menu as well and have that set to "Direct Stream Copy"
And then save the AVI.
Should only take you a couple of minutes to do, as long as Virtual Dub can load the files.

Are you rendering AVCHD video? If so you may need the 64-bit fix. Some people have said Vegas 11 does not need this, but others have said it does. See postings here for more info:

Sony Creative Software - Forums - Vegas Movie Studio Messages