Plutonium

Title says all, in DLC maps none of the characters will say any of their voicelines. I know it's not my audio settings or anything, since TranZit voicelines work just fine. On top of that, text on tooltips is often messed up on DLC maps, like in Mob of the Dead the Plane Parts tooltip is 'ZM_PRISON_PLANE_PARTS'.
Also, intro movies/videos for maps NEVER play. Anyone know how to fix?

There's a LAN Mode ONLY trainer which will do exactly this and a lot of other things. Just look it up. Only works in LAN Mode so you'd have to set up Hamachi with your friends. My friends and I do this.

Of course, thanks so much for your time.

I appreciate the response, but this didn't help. My friend and I have been running the game through plutonium.exe the entire time, and no update has occurred.

Everytime my friend joins my game, or I join his, we get an error saying our game is outdated as if there's a version mismatch, telling us to restart plutonium so it can update. Of course, restarting plutonium does nothing.
We both own freshly installed Steam copies of the game, and just installed Plutonium today. Something weird I noticed is whenever I try to join his game, the error will say something like "your game is outdated (r123456 vs r1051)", and everytime I restart the game to reconnect my version will have a different string of numbers attached to it, like it's somehow changing.
If anyone has any idea how to help, please do. Thanks for your time.