[Brano Kral]

Hey, I had a similar thing. My Vegas Pro 9.0 32bit on XP, then updated to 9.0c, stopped responding during editing or hung at 0% while rendering, with remaining time growing and growing to hours. Made my hair gray, dammit(:
I followed advice from some forums and opened preferences. There I changed number of rendering threads to 1 and disabled BOP rendering. Also defragmented the disk and ensured that pre-rendering files are stored on a drive with ample space. This might have helped to solved the problem, but wasn’t enough.
As many people with this problem report they found the solution in deleting some of the tracks or purging the unused ones (using the yellow flash button on the Project Media tab), I tried to go this way and it worked, hoorraaaay(: Some media files can be defective and prevent your work from being rendered. Such a file can be defective in this sense even if you can play or preview it no problem. What worked for me was disabling effects such as Sound Mixer or Vibrato on one of the audio tracks.

Another solution people report to be working is switching to Vegas 8 or Vegas 9 64bit.
Cheers and have fun,

Brano