Internet connection keeps going :(?

[Bangers & Mash, Baby ;]]

My rooter is working just fine so i doubt that is the problem. The internet connection goes and comes back often, when it goes i click on 'Connect to available networks' and the name of my rooter is ALWAYS there! Thats what annoys me! It disconnects but its still on the list, and when i click to connect to it, it connects with no problem! So can anyone tell me how to fix it? If it an be fixed? (:
errm well i have Vista, but it happens to my sister's laptop which is XP

[Sep]

It is probably your router. I have similar problems with my d-link router. It also has a lot to do with your OS I'm assuming you're using Vista right? Vista is horrible for networking. It will randomly disconnect or you will still be connected but you will lose your internet connection.