There are several utilities out there, designed to help with your Final Cut Pro install, that will back up user data, reset cache files and help with
other system maintenance issues. A new one that I saw mentioned via Twitter is called Final Cut Assistant. It takes a different approach than most by installing a drop-down menu to access its functions:

Besides the usual resets and backups, Final Cut Assistant also provides some options for importing and converting of media. I especially like the Import Copies… option which will take media, copy to a designated location and import that into your FCP project via an XML. Best of all, it’s free, though they do ask for a donation. Full details and documentation are available at the Final Cut Assistant website.