Invalid Format error

I know there are a lot of threads on this already, but I can't seem to find a solution that works for me. I have gone into the game.cfg thing and changed the resolution. That didn't work, I tried a few different ones. My monitor is 18" and is HD ready. I added the UserSetResolution=1 line, but still nothing. I can window the game and then it works (I've been testing with the training mode) but I don't quite know how to make the window larger and I can't just drag the edges of the window because my cursor won't come out of the window. I know this affects the quality though, so I am looking for a more permanent fix. Anyone can help?