To avoid the possibility of the game client jamming up at 100% as well as the PLAY NOW button (they are both flash software), I would clear out your browsers cache.
With your browser open, any page on any website will do, press...
....if you get any checkable options pop up on your screen, I would check them all, but read them first just to make sure you know what will happen. Then refresh your browser, or close and re-open it (achieves the same thing).