"Unable to load unicode.dll"

Every time I try to launch an Orange Box based game, e.g. Team Fortress 2, Garrys Mod; I am prompted with the error “Unable to load unicode.dll” and the game fails to launch. I have tried reinstalling these games repeatedly with no avail. All of the games worked without fail just days ago and nothing new has been installed/changed on my system since then. My computer is relatively new and I don’t think that it would be causing the problem. The specs are:

Windows 7 Professional 64Bit
AMD Phenom II 965 Quad Core
4GB DDR3 10666 RAM
ATI RADEON HD4870 1GB

Open the Steam window and right click on GMod. Then choose “Verify Game Cache” or something like that.