Laptop + Network = problem

Hi there. So I have Telia 24mb internet and ZyXEL router and I run my zepto laptop and it works fine in the whole house, but my little sister who has a fijutsu Simens laptop just cannot. We have two desktop computers connected firmly with cable and they work properly. I have tried everything I can but I can not do it.

When I join Sis computer I can connect and go out on the internet but when I press something to refresh the page is disconnected. So if I check the bottom right corner it says "connected to the local network," but it should be "connected to local and Internet" so I have no tips on why it disconnects the Internet after a few seconds of use.

I run vista on my computer and she has vista on it and it is xp on desktops. Does it have any significance?

All the tips and ideas that can help me solve this problem is welcome and thanks in advance.

Look up the DNS settings? Do not know if it helps, but it sounds as an obscure error.

What's it like during the Network and Sharing Center? Do you have an access to "Local and Internet", or is just Local? Is it just Local so go "Connect to a Network" and / or "Set up an connection or network."

See what shows at "ipconfig / all" from both your and her vista computer.