Since RVsitebuilder is developed to be stable with cPanel 11.42 and PHP 5.4.
It now has the problem on the server which is running with PHP 5.2. We are working on the solution of RVsitebuilder 5.2.11.

To fix the problem temporary, if  your server is running wth PHP 5.2:
1. Downgrade RVsitebuilder by running the command:
perl /usr/local/cpanel/whostmgr/docroot/cgi/rvsitebuilderinstaller/autoinstaller.cgi --rollback=5.2.10

2. Update cPanel in your server to 11.42, this will force to get PHP 5.4 automatically.