Invalid public movie atom was found in movie

I had a similar issue with ProRes 4444 files in FCP. After poking around Creative Cow's forum and reading some other posts here, the problem may be with iTunes 10.5 or Security Update 2011-006 - one or both of these is causing random Quicktime files to return the "invalid public movie atom" error. I was in the middle of editing a film on FCP, took a two week break, came back to this error. I did a reformat and reinstall of Snow Leopard, reinstalled FCP, and it worked. The Quicktimes open and play down without a problem. I would avoid upgrading to iTunes 10.5 and the Security Update for the time being. Hope this helps, and here's another discussion on the same issue:

https://discussions.apple.com/thread/3273077?start=0&tstart=0

ronfromsouthampton wrote:

Apple you need to fix this problem.

We are not Apple; we are just other users like you. These are user-to-user forums.

If you want to bring it to the attention of Apple, use the Feedback or Bug report forms.