After 4 days use I now know that 2.0 suffers from the same old problem that I had with 1.5 and before.

After the Firefox process is running (sometimes hours, more often days) the same thing always happens. What appears to be a blank toolbar, which you can't interact with, appears below the window title bar. At the same time, some web pages are rendered as if the screen around 2000 pixels wide.

To restore the normal functionality you have to close all the Firefox windows and reopen.

It happens on both the Windows boxes that I use regularly. This evening is the first time it has happened to me on 2.0

Here is an example of it happening on 2.0:

http://www.norman.cx/photos/links/firefox.png

When you make Firefox fullscreen it looks like this:

http://www.norman.cx/photos/links/firefox_full.png

I have tried to look through the Firefox bug lists to see if it a know issue, but it is difficult to know exactly what to search on (or even which area of the app has the bug).