Each time I open Firefox, I get a popup window that says "It is strongly recommended that you apply this update for Firefox as soon as possible." But I have updated Firefox.
But I have updated Firefox. And if I tell it to do the update, it runs and runs and runs but nothing ever happens. It has a 'view more information about this update' link but the link does not work.
Alla svar (2)
According to your user agent string you are not using the latest version of Firefox. It shows you have version 4.0, the latest version is 4.0.1
In the Help menu select "About Firefox", this should check for updates and then let you install the latest version.
If that does not work, try downloading the latest version from http://www.mozilla.com/ then installing it over your current version.
Did you ever install a Firefox 4 beta or release candidate version?
If you did then download the full version of Firefox 4.0.1 and uninstall the current 4.0 version before installing that new 4.0.1 version.