Are you getting an error during SQL Server 2012 setup referring to a hexidecimal value 0x00 is an invalid character? It appears this error comes from the pre-existence of the MSDE installed on the same system. The screen shot below shows the error on a machine where MSDE is installed and SQL Server 2012 Express Edition is attempting to be installed. The solution was to simply remove the MSDE (Microsoft SQL Desktop Engine) prior to installing SQL Server 2012.
Remove MSDE to Allow Installation of SQL Server 2012
Simply uninstalling the MSDE through Control Panel solved this issue.