Naughty Dog is aware of and fixing issues that rendered Uncharted 2 multiplayer unplayable.
Problems were caused by the most recent Title Update v1.08.
"We're aware that the 1.08 Title Update disables The Lab and double cash. We're working on it so those of you with TU1.08 can still play," tweeted Naughty Dog.
The Lab is an experimental playlist that enables custom-tuned gametype variations using the myriad variables the developers have previously kept under lock and key.
Double cash does what it says on the tin: offers games double the cash they would earn in game for a certain period.