''Every time I open Firefox, the navigation toolbar has returned to its default layout:'' See * '''Corrupt localstore.rdf''' - MozillaZine Knowledge Base<br>only downside is re-customizing toolbars View>toolbars>customize (take a picture of your toolbars first). <br>http://kb.mozillazine.org/Corrupt_localstore.rdf You can make Firefox '''Firefox 5.0''' look like Firefox 3.6.18, 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 5.0, or 4.0.1, look like 3.6)]. ''Whether or not you make changes, you should be aware of what has changed and what you have to do to use changed or missing features.''

That happens to me to sometimes. What I do when it happens is, right click on the toolbar and refresh the toolbar. It then goes to the way I have set it. Hope this helps you.