hmm... thanks very much! it solved the problem, sort of.
after checking integrity of the files it said two files failed and needed to be reacquired. Steam proceeded to download these two files and I was able to launch the game. The Strange thing is after i quit the game and relaunch, it got stuck at that update screen again. I had to do the checking integrity and redownloading again. Do i have to do this Every time i start a game now?