Sounds like to me your encountering a problem I myself had a long time ago. Every time the bar got to about the halfway point in loading the next screen, it would always end up booting me out. Strangely enough, it might be the signal is acting up. Mine did for a long time before it crashed (desktop, I mean) and I ended up getting myself a laptop. Try seeing if the signal for the game is cooperating with you. Think that might be a possible cause. Also, it would also work fine for me till that point. Hope this helps!!!!!
Also forgot to mention.... if you have too much history loaded in your browser, it won't function properly. Check into that if you can.