[pitay]

I do not have this issue, but I have a very customized about settings.

Here is the relevant about:config settings I have these changed for the URL bar:

  browser.urlbar.suggest.searches false
  browser.urlbar.searchSuggestionsChoice false 
  browser.urlbar.showSearchSuggestionsFirst false

Also for your urlbar you want to change it so it always shows the scheme and every part of the URL.

  browser.urlbar.trimURLs false

Stop Firefox trying to help with incomplete urls and loading the wrong site:

  browser.fixup.alternate.enabled false

Setting the above about:config entries should stop URLS you type being sent to a search engine and also stop some other surprises in the URL bar.