i figured out what was wrong with modern warfare. when i tried to start mw2 up it told me "Do you want to optimize your setting to fit your computer?" i selected no and it works perfectly. I still dont understand what's wrong with left4dead...
When i have the game running and i alt+tab out of it, it types perfectly. the problem only exists when im playing the game (ex. trying to move the character).
Well, whenever i play a fullscreen game like left4dead or modern warfare, the letters on the keyboard turns to numbers. for example whenever i press w or r it changes to a random number 0-9.