Ever since updating to OSX Mountain Lion, I can't access my FCPX files

When I went into FCPX after updating to OSX Mountain Lion, I was told I needed to update my FCP files or they wouldn't play. I clicked update and left it running all night (I have a lot of large files). The next day, after rebooting, I tried to access my files, but when I click on the "reel" symbol to load a project, the Apple wheel starts to spin endlessly. It goes on for hours, and finally I have to force quit the program. Everything appears to be there, but I can't bring anything up or work on projects. The second the program starts, the wheel starts spinning.