So In my house I have 2 Desktops, and 1 Wireless laptop connect to my router. The Main desktop, which is closest to the router and has XP, connects to the internet with no problem. The laptop is in my sisters room wirelessly, my desktop is in my room and is connected through an ethernet cord BUT it has Vista Home Premium. Now the problem is my desktop, with vista, has problems connecting to the router. It's been fine when we first got it, which was less than a week, but all of a sudden I tried to change the internet settings to get better dl speeds in utorrent but it didnt work and disconnected me from my router and didnt allow me to use the internet. So I changed everything back to the way it was and it still wont connect to the internet unless i restart my router/modem like 50 times.. Now it wont even connect, but for about 2 days the problem was on and off, having to restart my router over and now it just won't connect. I tried looking for a firmware upgrade but it i can't find any for Verison 6... anyways do you think it could be the ethernet card even tho i just got the pc?? let me know !!
Try a system restore on the computer and look for custom firmware or hacked firmware for your router.