I upgraded to Firefox 5 last night, and there is a bug with the script. I suspect it is a Greasemonkey compatibility issue, and would probably require a newer version, or at least one fully compatible with Firefox 5.
In AllInOne, there is an add-on where you can attack the player when you are viewing his/her profile. This doesn't work in Firefox 5. When you click attack, nothing happens.
My PC at work is still on Firefox 4.0.1, and it does work properly there. You may want to verify this.