i downloaded the demo version of vegas 4.0, and when ever i render a flie with any effect video or audio i get a blicking black backroun with a red x in the middle. but when i don't add anything to the file it renders just fine. i have no idea of what to do anymore. i tried rendering in just about every format. it still doesn't work. maybe it is just me making a stupid mistake i don't know. please help me if u can thanks.