Thanks for all of the quick response guys! Oops, I guess I didn’t realize that my Platinum 11 was worse. My friend recommended it and I wanted to try it. I guess I might just switch back to Pro 10. It still bothers me though (shouldn’t a 11.0 version, which is later version, be better than 10.0?).
Anyways, the avi files I have were downloaded online so I’m not sure about how they were created. Some of my mp4 files were converted using youtube converter. It may be a problem with the files, but they do play perfectly in media player.
Also, I tried the mediainfo program. It said Xvid, so I downloaded the codec, turned on sony vegas and the file could still not be imported.