Every now and then during campaign the server spits at me and disconnects everyone from the game. This tends to happen when we're finding a section hard and repeating it a few times. I've also noticed that during vs sometimes it disconnects everyone. Since I've been here, I think the whole party and my self have been disconnected about 4 or 5 times.

never come across a problem like that myself, i'm sure you'll hear from monkey soon about what his opinion is though.

very rarely I've seen this occur. I need to know a few things

1. Windows version vista/xp etc.,
2. When you get disconnected what is the error in the console (~)
3. Some people have mentioned removing\renaming the file \steamapps\common\left 4 dead\steam_appid.txt to something else, the file is recreated at start of game, select the newly recreated file and set it to read-only