I have migrated my FCP 7 over to a MacMini, upgrading the OS to 10.8 in the process. The first time, I just used my time machine to copy to the new computer, but all may Final Cut Material showed up with significantly altered gamma levels. I had to apply a filter to adjust gamma by .5 to return video to something close to the original on the previous computer (a MacPro running 10.6). I had done a similar migration to a different MacMini on 10.8 with no problems.
I started over, completely wiping out the hard drive and doing a fresh install of the OS and then FCP Studio. Same results. The files are not corrupted. Those exact files play fine back on the 10.6 computer. What could be causing this? OS and this one computer seem to be the only variables.
Mac mini, OS X Mountain Lion (10.8.3), i7 processor