What happens if you bypass DNS by typing the IP address directly into the URL?
http://216.115.108.243/[goats.cxyahoo]
On several of my linux servers, I will often times find in the aolserver logs messages that gethostbyname has temporarily failed. I can't imagine why it would fail aside from bad isp (or maybe bad sysadmin (me)), but I would think that if DNS is failing for whatever reason, that would be a good reason for Mozilla to choke.
And what happens to Opera, Lynx, or Konqueror at those times?