Is Comcast Territorial?

Hello,
One of my users is using a Gateway Solo laptop and has had trouble conecting to the internet via her exsisting connection at home with Comcast cable. I have gotten the laptop to connect to other ISP’s at other locations just fine(using broadband and dial-up). Her Comcast connection works fine on her exsisting desktop but not the laptop. Is comcast configured to only recognize the original pc it was set up on? Any Suggestions? Thanks!