So this was happening with this one scene before I installed 8.0c and was kinda sorta hoping the update would fix it. The project is HD 1080-24p (1920x1080, 23.976 fps), it's length is 00:08:06;27. It's got a variety of media including some large images (one is 5912x4000 PNG). Vegas doesn't "crash" per se, it just gets to around 50% and hangs indefinitely. At one point I managed to render most of it to a new track, including the segment with the large images, and even with those still get the hang. I've even tried removing those particular images (since that part is rendered to a new track) and even still can't render it out. 
Suggestions?
- Ray
Some of my stuff on Vimeo 
www.undergroundplanet.com