I have converted my DVD collection to MP4's over the last few years. I have about 400 of them, no big deal they have been in iTunes forever. But I just upgraded to a new version of iTunes and now some, not all, are showing up as gray boxes saying, "This file uses quicktime that is no longer supported." As far as I know they were all converted with the same settings using Handbrake (possibly different versions of handbrake). Anyone else see this? Any easy fix except for going back and reconverting those files? I would have thought that Apple would have been backward compatible with their files. Thanks!