Well, this is one of those situationewhere deleting the preference file would actually be useful, because that is one of the things stored there - but you alreday did that...
Are you still on 10.6? Your profile says so.. although it has to be 10.6.8 then.. as FCPX does not run on previous versions.
Do you by any chance have a Window Manager or extension installed??
In addition to trashing preferences, you could also try trashing the window layouts.
Option-click on the Go menu in the Finder, choose Library; navigate inside the Library folder to Application Support and the Final Cut Pro. Now trash the Layouts folder.
Start FCP again. Hopefully, that may solve the problem.