HideoK on 12 November 2009
For anyone looking to play Spec Ops co-op and is getting the error saying the party is no longer available I found an incredible fix online that I really didn't think would work, but I tried it anyway and it worked.
1. The party leader sends invites to all.
2. Before accepting the invitation to join the party, press the PS button and log out of PSN. (requires you to quit the game)
3. Log in again and now accept the invitation.
Or you could wait until Friday for the next patch which should fix this.
