Jailbroken 4.50 PS3? I'm assuming you had a 4.50 and E3 flashed to 3.55 then spoofed to a higher FW? Or what?
You should just put in a modded .eboot, preferably one by Choco..
If you don't know what that is, don't ask me 'cause I have no clue either I don't even have a JB.