The thread at http://reviews.cnet.com/5208-6142-0.html?forumID=5&threadID=42169&messageID=494356 suggested many things.
But you didn't supply the contents of your HOSTS file so I can't rule that out. Supply what is asked so we can have the clues needed.
I am running Windows XP Home Edition and cannot access www.usps.com. I receive a time out message. I use zone alarm pro for my firewall and panicware pop up blocker and have tried access without these running but still cannot get to the site. This problem has been with me for approximately 2 months and I have tried various browsers (netscape, yahoo, ie, etc.). I am now running firefox and still cannot reach this site. I know the site is operational as I can reach it with my dial up notebook PC. I am using a cable modem. Rebuilding my system is an option but there is no guarantee this would fix the problem. Any help and suggestions are appreciated.