hello JiveTurkey, please Update Firefox to the latest release and see if you can replicate the issue then when you once launch firefox in safemode for testing purposes: Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Update have been disabled by the System Administrator (it's a work PC), so that is not possible for me.

Thank you for the troubleshooting link though. I have tried Safe Mode, where the problem still occurs. I have also created a new profile, where the problem does not occur! So it is something in my profile that is causing it.

Try to set the browser.urlbar.autoFill pref to false on the about:config page.

See "Prevent Firefox from automatically completing URLs":

• https://support.mozilla.org/kb/search-your-bookmarks-history-and-tabs-awesome-bar

So the Sys Admins just rolled out ESR 24 and my problem is fixed. Thanks for the suggestions guys.