OSStatus error 38

I was getting this error when using Quicktime Player 10 to convert an mp4 to iTunes for Apple TV. I looked on the forum and several other people were having this issue as well but there was no answer. The discussion was "archived" so replies weren't allowed.
I discovered I was able to convert it using a shareware program called ffmpegX - get it here http://homepage.mac.com/major4/