Video levels on FCP 7 Prores are different than the original material

I converted a bunch of h.264 material through compressor to Prores and proceeded to edit the project on FCP 6. I recently upgraded to FCP 7 on this one machine and now all of the video levels are way off (things are blown out that weren't before). If I import the original h.264 content, the levels are fine. Additionally, I have tried this same project on other machines and the same thing happens. I feel like I have read something like this before and the solution evades me. Please do help.