After cheaters and griefers disrupted the fun in the Xbox 360 version of zombie shoot-fest Left 4 Dead, Valve has quickly issued a fix.

"Valve has released a server-side fix to deny the recently reported cheats on all dedicated Left 4 Dead Xbox 360 servers," read a Wednesday e-mail from Valve marketing head Doug Lombardi.

"The fix is designed to halt the cheating behavior on the dedicated servers, which accounts for the majority of the co-op and Versus modes of play."

He added, "A title update for those playing on user-hosted servers and/or via system link will be released in the coming days."

Reports of hacks in the Xbox 360 version of Left 4 Dead emerged earlier this week that detrimentally altered spawn points and enemy encounters. A Kotaku reader said yesterday: "Versus mode is a blast, but recently, I joined a game and found myself in a safehouse at the beginning of a chapter. Suddenly, about 30 witches spawned in the safehouse with me followed by two tanks."

For the uninitiated, Valve intended safehouses to be safe, and a single witch or tank enemy can wreak havoc on a group of players.

The modder posted a video of the different kinds of alterations one could achieve, even providing a tutorial on YouTube. The modder has since obscured the tutorial section of the video, stating, "Sorry, no more tutorial. I am not trying to 'ruin' this game. This got WAY out of hand. I was not expecting this."