I love Mozilla Firefox and actually prefer it to Google Chrome, but if there could be a list of its very annoying features, the first on mine will be the URL AUTOCOMPLETE idea. Why on earth should Firefox be telling me what it thinks I should be thinking? What an insult!
The following is a guide on how to disable it.
Open the FIREFOX OPTIONS / SETTINGS WINDOW: Click the orange FIREFOX pulldown button >> click OPTIONS >> click OPTIONS
On the Options window, in the PRIVACY tab, find the LOCATION BAR section and select NOTHING "when using the location bar".