Why has my Firefox quit working?

[Josef Lowder]

Why has my Firefox quit working?

While I have a solid Internet connection and I can connect
with either ftp or with my Konqueror browser, I just started
getting the following error message from Firefox:

Server not found
Firefox can't find the server at www.google.com.
* Check the address for typing errors such as
  ww.example.com instead of
  www.example.com
* If you are unable to load any pages, check your computer's network
  connection.
* If your computer or network is protected by a firewall or proxy, make sure
  that Firefox is permitted to access the Web.

I have double-checked that the URL addresses I am trying are correct.
My network connection is fine.
I've made no changes in Firefox.