This is old problem, but while netenberg not release new fantastico which supports newest cpanel release, this problem still appears.

Fantastico, the most popular auto installer  plugin for cpanel, have compatibility problem with newest cpanel release. Newest cpanel release using register_global=off for their php backend, and this not supported by Fantastico.

Since May 2008, Netenberg promises will release updated fantastico that compatible with latest cpanel release, but until now no update release from netenberg, so we must temporary fix this problem until they release.

Log into your server via SSH as root and create/edit the file /scripts/postupcp via your preferred text editor (nano, vim, pico, etc.).

If the file doesn’t exist or is empty, paste in the following code:

#!/bin/sh
perl -p -i -e 's/^.*register_globals.*=.*$/register_globals = On/g' /usr/local/cpanel/3rdparty/etc/php.ini
perl -p -i -e 's/^.*register_globals.*=.*$/register_globals = On/g' /var/cpanel/3rdparty/etc/php.ini


If that file already exists and has entries in it, add the following to the bottom of that file and save changes:

perl -p -i -e 's/^.*register_globals.*=.*$/register_globals = On/g' /usr/local/cpanel/3rdparty/etc/php.ini
perl -p -i -e 's/^.*register_globals.*=.*$/register_globals = On/g' /var/cpanel/3rdparty/etc/php.ini


Make sure permissions are set correctly on that file:
chmod 0700 /scripts/postupcp
Then run that file once:
/scripts/postupcp
If these steps not successfull, you can try to do following command :
/scripts/makecpphp
Wait until finish then re-run again /scripts/postupcp

Hope this help..