PC connection issue

[Bartylby]

it's not with me, it's my brothers computer.

His computer can only connect to the internet when mine is on... it makes no sense. I've checked all his settings and it's all the same as mine minus everything that shouldn't (mac addy, ip, etc) and when my computer is off it wont open anything that uses the net.
Even though when i go check his connection in my network properties it says connected(even though when i try to "repair" the connection it won't work unless my comp is on as well) and the card is working properly in the cards settings.

I've checked all his tcp/ip settings, it's all set to auto (same as mine) as i have cable, and my router is set as the dchp server and i connect just fine, it's just i have to have mine on or he's sol.

any idea's ?

[Norellicus]

Just for grins, do an ipconfig /all of yours and his machine (separately) and post them here.