Hello David, I've been having the same problem. The viewer filled my whole screen, and after I cliked on a menu item, every thing was greyed out and I was stuck on that screen.
I had to reboot several times to get out of this situation, because I don't know how to get into the shell and kill the process. I found that pressing Alt and the spacebar together, I got a drop-down menu and clicked minimize and then I was able to continue on. Good luck Jack McGill
