hi.
I have the exact same problem.
I’m running on an MBP 2.8Ghz i7; 4 Gb memory; with a NVIDIA GeForce GT 330M 512 MB; Lion OS.
This thing it totally random. I can export the same file 3 times, and those “corrupt frames” will show up in different parts of the movie.
Plus, I noticed that if I use Final cut (or any other program at the she time while I’m exporting it, those corrupt frames will be more frequent.
Did you find a solution to this problem?
thanks