So, every time I try to render an mp4 file of any kind in Sony Vegas Pro 11 it gives me this incredibly annoying and vague error, "An error occurred while creating the media file...." "An invalid argument was specified."

What I am wondering is if anyone has the solution to my problem? Vegas Pro 9 renders mp4 files flawlessly, and, I would go back to 9 if it weren't for how once I have worked on a file in Vegas 11 I can't open it in 9, which is fair enough.