Why would you go to v.4? Firefox 4 and 5 are the same thing. Go back to 3.6 instead. [http://www.mozilla.com/en-US/firefox/all-older.html Firefox 3.6 (The last good version of Firefox)]

If this is a matter of the toolbars they are customizable... You can make Firefox 4.0.1 and '''Firefox 5.0''' look like Firefox 3.6.17, see numbered items 1-10 in the following topic [http://dmcritchie.mvps.org/firefox/firefox-problems.htm#fx4interface Fix Firefox 4.0 toolbar user interface, problems (Make Firefox 4.0 look like 3.6)] You won't see much difference in 4.0 and 5.0, version 4 is at end of life (no updates) For those that really need an earlier version of Firefox * ftp://ftp.mozilla.org/pub/firefox/releases/ :or with the latest of version 3 * http://www.mozilla.com/firefox/all-older.html When reinstalling Firefox from a download, Firefox must be down once the installation starts. When the installation finishes, don't let the install start firefox for you. Instead end the install and start Firefox in your normal manner, thus preventing creating a new profile which does not have your bookmarks, cookies, etc (but your old profile would still be around and would).