Ubuntu 12.04, kernel 3.2.0-33-generic...
Just did a "apt-get upgrade" and firefox broke. It now starts up with a tiny window that is unusable and which cannot be made bigger. I use a custom desktop based on plain ubuntu, using the Sawfish window manager, which has been my WM of choice for years.

Here is a screenshot of the firefox window:
http://imgur.com/A9TDW

That's as big as the window gets. F11 doesn't make it bigger. My keyboard shortcut to maximize the window doesn't make it bigger. Can't drag a corner to make it bigger. Started in safe mode and with a brand new firefox profile and the same results. All other apps behave normally with respect to window sizing.
Screen resolution is 1920x1080.
Firefox version is: 17.0+build2-0ubuntu0.12.04.1

When I switch from sawfish to the regular gnome window manager, then firefox does start up with a normal window and is resizable.