[Richie Nuttall]

I have had this issue, what i was doing was shooting video with the iphone and editing and trying to render to mpeg or avi.
It wont allow this so what you need to do is change the input video tomatch whatever output you want. So in my case i used “Any Video Converter” as its free and will do all formats, well most and converted my footage that was shot in .mov to .mpeg then i added it to vegas and my edited clip and rendered to .mpeg and all worked great.