disable search in the address bar 

Hi oitconz, setting keyword.enabled to false prevents Firefox from sending your input to your default search engine. However, I don't think what you're describing is a search problem.

Firefox will send input that looks like a valid server URL to your DNS service provider. If you type a word with no dots such as localhst and DNS says it does not exist, by default Firefox will retry with www. before it and .com after it. That is a separate feature you can disable.

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) Search: In the search box above the list, type or paste keyw and pause while the list is filtered

(3) Double-click the keyword.enabled preference to switch the value from true to false

(4) Fixup: In the search box above the list, type or paste fix and pause while the list is filtered

(5) Double-click the browser.fixup.alternate.enabled preference to switch the value from true to false