Hello Andrew.

I think this happens when right clicking the toolbar and accidentally selecting (deselecting) an entry, right?

I don't know of a way to disable that particular contextual menu, but it's definitely possible with extensions. Try searching at addons.mozilla.org. Or you can try the developers' forums to explain your problem and request an extension, if it doesn't exist. Or you can build one yourself if you have the time and skill/will to learn. I'm sorry that this isn't easier to solve.

To recover lost toolbars and buttons, this article will help you:

https://support.mozilla.com/en-US/kb/Back+and+forward+or+other+toolbar+items+are+missing

Morbus Thanks. I at least have a method to recover from the problem. Previously I had to totally remove Firefox and re-install. I've gone through all the add-ons. No luck. I will try the developer centre. Thanks Andrew

Try to add this code to userChrome.css below the @namespace line. @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */ See http://kb.mozillazine.org/Editing_configuration#How_to_edit_configuration_files

#nav-bar, #toolbar-menubar {
 visibility: visible !important;
 height: 26px !important;
 min-height: 26px !important;
}

You can look at the Window's accessibility features:
Windows 7: http://www.microsoft.com/enable/products/windows7/default.aspx - Accessibility in Windows 7
Vista: http://www.microsoft.com/enable/products/windowsvista/
XP: http://www.microsoft.com/enable/products/windowsxp/default.aspx

See also:
http://kb.mozillazine.org/Accessibility_features_of_Firefox
http://www.accessfirefox.org/ - Access Firefox Because the Internet is for everyone.