TBB 3.0a3 "Tor Network Settings" page blank for some Windows users
https://blog.torproject.org/blog/tor-browser-bundle-30alpha3-released#comment-33380 says """ For me (on Windows 7), on running Start Tor Browser.exe, the Tor Network Settings box appears, but it is empty.
It doesn't go into a "Not Responding" state, I can move it, resize it etc, but it's completely empty and nothing happens after this point. """
https://blog.torproject.org/blog/tor-browser-bundle-30alpha3-released#comment-33413 appears to report the same thing.