Valve has released a new update for Left 4 Dead 2 on PC which fixes a bunch of issues related to multiplayer versus mode.
Tanks have been improved with a new stasis mode, the points system for Chargers will now make a lot more sense, and friendly fire has been made less annoying.
More details in the words of Valve below:
While we were testing other changes with the Charger, we were bothered that doing the right thing did not give you the best score. New players were often confused by this lack of feedback, so we fixed that.
* Charger now receives 300 points for any Survivor that is insta-killed.
* Charger now receives 100 points for any Survivor that is insta-incapped by a charge.
* Any infected that causes a Survivor to stumble into a "ledge hang" situation will receive 50 points.
Friendly fire is never fun, especially when it really isn't friendly fire. So in both Versus and Co-op we wanted to remove those times when you receive a friendly fire warning for shooting through an infected.
* Bullets that first pass through an infected character before striking a Survivor are now ignored as friendly fire.
Failing at the Tank is miserable experience. We all know the feeling when you are trying to explain to your team - but he was already on fire! So we did some work there.
* Tanks go into a stasis when they spawn and leave stasis when the human player takes over.
* Tanks do not attack when they are in stasis.
* Tanks in stasis are invisible but still show a glow to the infected team.
* Tanks in stasis cannot be set on fire.