I bought a new wired Xbox 360 controller to play Devil May Cry 4 on PC but I've been getting this problem were down on the Left anolog makes my character walk, while pushing all the way in one direction should make the character run, down does not. I've noticed this in Mafia II as well, I figure this is either a driver problem or a controller problem, although I'm not sure what I have to do, I think my drivers are official and up to date.

Sounds like a driver problem, or a button mapping problem.