My project is about 15 minutes long. Original footage in AVCHD, converted to avi by Neoscene, because Vegas had a hard time accepting those files to the timeline, it would close after a few seconds. Since the AVCHD files were converted to avi, I was able to import and finished editing. The problem now is that Vegas can't finish rendering. It shuts down at the same point into the rendering process. The part that WAS rendered is playable, with no problem, excellent video and audio quality. The template I chose is Sony AVC, 1920 x 1080, 30i, 16 bit rate. I'm not 100% sure on the bit rate value, I'm at work, will verify that piece of data when I get home.

For comparison, I was able to finish rendering and burn to a DVD, same template and everything, a SHORTER project, only 9 minutes long.

Any idea where to start looking for the causes? Does Vegas keep a log of why it shut down?
Thanks,

Vegas & Cineform has issues you won't really find a cause but I find that rendering out a project out in sections say 3 minute parts to Cineform then re-combining all the parts into another project and rendering out to Cineform again without the need to re-render helps. Once you have a master file then use Adobe Media Encoder to transcode the Cineform master to whatever format.

Another thing that helps is if it crashes at the same place all the time re-convert that section of footage with NeoScene.

This could be a heat problem.
When did you last take the side of your case off and blow out the dust bunnies?
Core Temp (http://www.alcpu.com/CoreTemp/) is a good and free CPU temperature monitor.
Run it during the render and see if things are heating up too much.