Please help... Vegas Movie Studio crashing

[Spauld]

I installed Sony Vegas Movie Studio a few months ago and have edited and burned a couple of DVD's with no problems. However the project I'm working on now is larger, and just half-way through my project, I cannot even keep the program up and running. I get an error message that says "An exception has occured and Movie Studio needs to close". I have recently been able to view the details. Of course there's lots of computer code in the message, but some key phrases seem to be "access violation" in Module "mcmpgvdec.dll"

I installed more memory and reinstalled the program, but nothing seems to work.

I have no idea how to correct this (very frustrating). If anyone has any suggestions, they would be greatly appreciated.