Sounds like you're behind a firewall or your router is blocking the IP. I personally had to disconnect myself from the router and plug my PC directly into the modem to be able to use the blizzard downloader.
Your only other option would be to use the mirror sites and download it directly.
On a big patch day, I put my computer in the router's dmz until the patch downloads (be sure you keep your windows firewall on). If you have multiple pc's, you must do this one at a time.
google search for wow patch, and one of the top links will be to something 3D gamers, go there and grab it. depending on your speed you could get it in less then 1hr.