I just got the game on Steam. Downloaded and installed. It worked, but I changed it from full screen to windowed mode. I minimized it and brought it back up again later. I can see and move the mouse pointer around, but clicking on the start menu buttons does nothing. I uninstalled, downloaded again, and reinstalled. It kept the option of windowed mode and the start menu buttons do nothing when I click on them. Can't start the game or access anything beyond the menu. I see the mouse and the GC2 animation of the space station. Any ideas? Thanks so much.