I have had that happen before, closed/reopened steam and all was well. I have not been "perma-stuck" like you may be. Open/close a few times to see if that goes away.
That's weird. I think I played all of them through before I tried versus, so I don't know.
Try playing them through singleplayer with easy difficulty. Didn't take me more than 15 mins per campaign.
It's also worth knowing the campaigns before you hop into versus. Most of the people know the maps by hand and get irritated if you get lost in the first room.
TG-E1st TacticalGamer European Division | Team up with us today! Minä kaskean, vihan liekillä kylvän veristä ohraa. "See the world, while it's still there" - Madventures
I've noticed it when they are updating the servers. Essentially L4D cannot get your steam info so it does not know that you are you and will not connect to anything.