Why would Final Cut Pro 7 lag on one user account and not another?

[dassin48]

Hey all, I hope I placed this question in the applicable forum.

I just purchased a new 27" iMac 3.1 Ghz Intel Core i5, 16GB RAM, AMD Radeon HD 6970M 1024 MB. Just went to Mountain Lion a few days ago. I installed a licensed version of Final Cut Pro 7 on my account (Admin). However, the program immediately started to lag. I click on ANYTHING on the FCP interface (Modify, Sequence, etc), it immediately stalls for about 3 seconds, and then color wheel spins for a few more seconds before the menu finally drops down. Footage logs fine but the same thing happens when I drop a small video snippet on the timeline and try to play. Stall, color wheel, then it needs to "catch up" before the footage starts to play.

Could this be some kind of hardware issue? I don't think it has anything to do with footage formats or anything like that. I did a little research and someone said to open FCP on a different user account. I did and low and behold, FCP works swimmingly. Very odd. This particular person suggested to uninstall and then reinstall FCP on the main user account. I did. But I still have the same problem with the stalling and lagging of the program on the main user account. Now no footage is logged. It's just an empty project and I'm still having these problems with lagging.

I ran diagnostics on my HD and everything is perfectly fine. Does anybody know of what could be causing this? Thanks!