[Ryan Staton]

i have recently experienced the same problem.
no matter how many calls to customer service the problem still continued to exist. But, then i realized that the version I am using has got to be at leat 6 mothes to a year old so i figured there must be some updates available that may fix the problem. poking around in the drop down menues i stumbled upon an option.

Click the “Edit” tab; then click “clear edit history”. sony vegas saves every editing function to provide a history database for your project recording every click you make within your project from the moment you begin. (i do not know how to view them). sony explains while clearing the editing history that this will greatly increase disk space and reduce memory costs. so i cleared the editing history and started rendering to burn a DVD and it worked!

please note i am an amature when using this software and probably wont be able to answer further questions. this is just something i stumbled upon after many options in attempting to solve the problem. it worked and i am currently satisfied.
i hope this helps!