Unable to access paticular web page

I have a user with a laptop who is trying to access a particlar link on a web page. He has no problem browsing the web and even the home page of the website and other pages within the site. The problem occurs when he tries to access a particular link that should take you to their mail access, it attempts to launch a new page and comes up with a page not displayed error message. Now I can access this link from my own pc, so I know it’s not a problem with the link. The only difference is that my OS is win 2000 pro and his is XP pro.