Intetnet connectivity

Here’s an interesting one. A client of mine just got DSL reinstalled, and can’t get to a couple of websites. One of them is www.irs.gov. I can get to both sites when I go in their office with my laptop and login to their network. I have checked and setup both IE’s with the same settings, and still can’t get it. I have run out of ideas, any suggestions would be greatly appreciated.