I’ve had this nagging issue for months now.   Every time I go to restore a database from a backup file, I cannot click the Files menu in the left sidebar.   This didn’t happen in SQL Server Management Studio 2008.    But it happens every time in SQL Server Management Studio 2012.
I enjoy using SSMS, it works well for my needs.  So it got very frustrating that it would lock up when I needed it most.
I finally took the time to research and thought maybe a newer version had been released since I downloaded it.  So installed the SQL Server 2012 Service Pack 2 update and sure enough, it fixed the problem.
The download link for the Service Pack is http://www.microsoft.com/en-us/download/confirmation.aspx?id=43340