How do you sudo?
just change the top level structure for the linux equivalent
C:\Documents and Settings\Virtual Box\Application Data\Mozilla\Firefox\Profiles
would be ~/.mozilla/firefox
copy the *.default folder
edit .mozilla/firefox/profiles.ini with the folder name
if you have windows only addons like IE tab start firefox in safe mode (firefox -safe-mode)
If the window decoration doesn't change, then try Radiance instead:Code:gsettings set org.gnome.desktop.wm.preferences theme Ambience
I am using Ubuntu 12.10 beta and for some reason I can't change the window decoration using Unity, just Gnome-Shell. However, even with Gnome-Shell, Ambience decoration is not working. Perhaps you are suffering the same issue.Code:gsettings set org.gnome.desktop.wm.preferences theme Radiance
When you say "eventually" is it a long time? Does it involve active browsing or does it go away even if Firefox is open but not being used?
Can you correlate it with any action on your part? For example, in the two images you provided, the "normal" one doesn't have the find bar at the bottom. The problematic one does.
Do you have other options when you log in? My thinking is that while Firefox will be the same, you may get an idea of whether this problem is related only to GNOME Classic or not. For example, do you have the GNOME Classic No Effects option? If so, what happens when you run Firefox?
de gustibus et coloribus non est disputandum -- Wiktionary