Error! Variable "$blendframes" is multiply defined in material "particle/smoke1/smoke1_add_nearcull"!

Left 4 Dead 2 Official Dedicated Bugging Going Black Screen

As the keywords suggest, when starting a game, the game goes black. If you whip up console, there is this error. Which I know other people may get when they try to start up an Official Dedicated game. Anyone know why this is?