A better place to ask these types of questions is,
http://www.2pop.com
best of luck.
if you could give me a little more info I might be able to help. Did you do any upgrades recently, any new software/hardware. Have you changed some preferences, new projects. What was the last thing you did with FCP. If all else fails, and you don't have any projects that you are working on right now, I would reinstall, it might do the trick.