Hp with XP Pro won’t connect to wiireless network or to cable

I have a HD Pavilion Notebook that travels with me–attaced mostly to my home wireless router through comcast, my office network and router through Verizon and a remote frequently visited business location through Comcast. My wireless and cable internet is fine in my office and home, but will not work with wireless or with the router at my remote location–yet every other laptop and desktop there work fine with this. It usually works fine, but suddenly nothing. Is it the settings on the computer or could it be the Comcast Router and specifically my computer configuration? What’s up with this?