Re: Firefox freezes ONLY when entering a search with Google, must close FF via task manager in order to restart it - Windows 7 64 bit. Was not like this always.
This can happen if you or an extension have modified network.http prefs.
You can check the network.http.* prefs on the about:config page and reset all bold user set network.http prefs to the default value (network.http.proxy.keep-alive should be true) via the right-click context menu -> Reset.