campaigns conflicting with their own parts.

[CommandoRyanbo]

I've had everything turned off, I've redownloaded, checked and unchecked every multiple part campaign but each one I have; Back to School, Dead Before Dawn, Suicide Blitz 2, I Hate Mountains, are all conflicting with their own campaign parts. When l4d2 tells me to check my command console for details it gives me the error message:
Error! Variable "$blendframes" is multiply defined in material "particle/smoke1/smoke1_add_nearcull"!
Material trails/smoke used by particle systems cannot use proxies!
What does this mean, and how can it be fixed.

[CommandoRyanbo]

My command console also gives me this error which sounds fishy as well:
CGameUIConVarRef cl_ignore_vpk_association doesn't point to an existing ConVar

[Notastoner]

I started having this problem recently also.

[Stark Raven]

The smoke particle error is always there. As far as I know, there's no way to get rid of it. It also does not pertain to campaign conflicts.

I believe the campaign conflicts have to do with the latest update. It's changed the way the game handles the campaigns and maps, although I don't know how, and don't seem to have been particularly affected by it.
If the campaign parts are not actively conflicting with each other, i.e. causing them to not function properly, then you don't need to worry about the conflict. If the campaign parts are screwing each other up, then I recommend manually downloading the campaigns from a site such as L4DMaps as one single file.