I've had problems since updating from the 2.x series but would not go back because of security concerns
Firefox 2.0.0.20 was the last in the 2.x series and it's no longer a secure version.
There's no longer any support for the 2.x series security.
http://www.mozilla.org/security/know...firefox20.html
There's always 3.5 to try
http://www.mozilla.com/en-US/firefox/all-rc.html
http://www.mozilla.com/en-US/firefox/3.5/releasenotes/