One problem that I can think of is that since you didn't update the game on the pc, then the game is not "in-sync" with the game on the servers. Another problem is that over time the game has grown and progressed to the point where your computer hardware (cpu, gpu, ram) likely don't meet the requirements for the game. Now days, a lot of games will post on the internet the minimum system requirements to play the game. One of those games is World of Warcraft, if your machine doesn't meet the minimum requirements then when it does play, it either plays like crap or it doesn't play at all.
Check out the website, "canirunit.com", it will let you know if your system can play a particular game.
