Well, I'm not even sure what happened but the game is now working. A couple of additional restarts and changing Steam from Offline to Online seems to have fixed it for now. It's weird because I had already followed all of those steps and it didn't seem to fix the problem...now it's magically working. Sorry if I can't be any more help, but I changed nothing and the game started working.
I think I'm just going to run the game on my PC which seems to be a much more stable version.
