SQL Server 2012 Installation Error
Because SQL Server 2012 isn't out yet, and we're dealing with beta code, this is probably best handled as a support request at Connect.Microsoft.com.  Include all of your logs, and they may be able to diagnose it.

If you do want to pursue it here, include the full build number that you're using, and expect to hear people answer with, "You should try again with the latest release candidate."