(adsbygoogle = window.adsbygoogle || []).push({}); Okay, heres whats happend.

First of all you will have realised that they have taken the Message Party invite or whatever method in Modern Warfare 2, So you basicaly send a message to invite to your game/party. This is what ****ed it up.

Many people logged onto MW2 on the release date, those people also wanted to play parties with their friends. They sent these new "Message Invites" to their friends and hoped to get in a party. Heres what went wrong:

With so many people online at one time, and around 80% of these people sending invites to their friends, All of these messages that are sent are crashing and lagging the Playstation Network server, Causing EXTREME lag. So if you were trying to connect last night to someone and it gave the message: Game session no longer avalible.
Or Game session no longer valid, This is because of all of the people online sending these messages lagging the PSN + MW2 Servers. Then today when i got home from school, i realised no one could even get online to play matches.

Okay so if you are still reading:

I recon that the patch will be a hotfix, or possibly a download. i remember downloading a patch earlier but that did nothing. So just be patient and hopefully it will be fixed soon

*EDIT*

Okay, i have found more infomation about the matter.
Firstly i will state that the patch/fix will be here by Friday. So after waiting 2 years for the game, we have to wait longer.
Secondly:
The patch was 1.02 i think, and this is actualy what made the whole sittuation worse. It was intended to fix the trophies, but instead screw up the multiplayer. That explains that message you get when you try to go online, where it just says "Fetching ranks and unlockables" this is due to the patch, so we would still be able to play online but just not in your parties. So theres some more infomation for you.

-xTaKeYoUDoWn.

Please rep if i helped, and nom.

this is why they should have had beta

Too right mate