That is one of the chief reasons I hate STEAM.
So its always good to play the game on offline mode (Steam client), while playing single player.
I agree. Playing offline does prevent Steam from installing patches. However, I have a number of programs requiring constant internet connection and it is easier for me to remain online during game play. That said, I do NOT play Left 4 Dead in any of its' online modes - I play all of the games I own in single player mode only.
there is 1 thing you can do about this and that is to not keep the game up to date.
right click on the l4d2 line in the my game tab of your steam client and choose options in de menu, now go to the updates tab and select do not automatically update this game.
now click close and it will not update the game anymore.
I believe Rickmon said
[Edited by NobleCrusader, 12/19/2009 3:16:49 AM]