(adsbygoogle = window.adsbygoogle || []).push({}); right i had a patch on my 3.55 ps3 and the patch worked fine people could join my game session and i could join there partys and stuff , but i thought of using the Elite mossy v8 Derrektrotter edit so i put it on the 3.41 ps3 and it worked fine , so i transfered it to my 3.50 and the playlist changed back to the old old one with 3rd person cage match and stuff so i thought okayy .? then i went into a private match and noone can join my session so i said to my mate inv me to a party and i couldent join and now i cant play online either ?? HELP PLEASE

Redownload the patch, you might be changed the default_mp.self for another and its bypassed, u possibly tried to 11th or something...
Redownload all savedata ( Delete MW2 savedata put the game and download 1.11 version) change the patch and transfer.

heres what happned.
you downloaded a patch with a 1.00 mw2 playlist on it.
you need another patch WITH the 1.11 playlist on it in order for people to join.
you probably downloaded a patch with 11th prestige on it.

you put the 11th prestige thing. YOU CANNOT use 11th prestige and play with other people

on you settings make sure ur proxy server is set to do not use!