How long does it take to process? What happens does PHP on your server crap out?
Basically we need to know what happens. If nothing happens and your PHP is timing out reading the threads on here about using GD2 and its constant theft of PHP memory which haults PHP this might help you
http://www.photopost.com/forum/showp...90&postcount=2
Now if there is some other issue your trying to get across let me know