During the tutorial, it seems like the memory dump goes blank for me (it loses its scroll bars, and loses its contents) -- http://i.imgur.com/ta9iykd.png
This is Firefox 25.0~b1+build1-0ubuntu0.12.04.1, on Ubuntu 12.04. I'll try it on something more modern when I get home.
Additionally -- on the first "Yay!", I don't get the nextlevelbutton (which seems to be what it wants me to do next); gray_bg and youwin_outer remain display_none. I have to go manually put them in place in order to proceed on.
This is Firefox 25.0~b1+build1-0ubuntu0.12.04.1, on Ubuntu 12.04. I'll try it on something more modern when I get home.
Looking forward to it!