Cannot Approve Images

[amcb10]

I have just installed the latest version of the gallery with SMF 1.1.11 and everything went fine. I have since noticed that if I go to approve an image I get this error....

GET to /My URL/index.php not supported.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Can anyone shed light on this error?

[SMFHacks]

This is caused by an issue with mod_security either disable it on your site or full this guide here
http://www.simplemachines.org/community/index.php?topic=34270