after the update (just update and i guess it firefox 12? i can't see the version because whenever i want to see it the box didn't appear), i can't browse using firefox. when i type the website that i want to go and enter it didn't do anything. and also after wait long time there's a box appear and said A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete. Script: resource:///modules/NetworkPrioritizer.jsm:175 (this is the screen caps http://img27.imageshack.us/img27/6823/erroruk.png) i already restart my computer and also turn it off, wait for one day and it still same.