Connection with MN-100

I have a wired network using a Microsoft MN-100 router.
This network has been running since last November with no
problems. I use Road Runner as my ISP. It is connected
to a cable modem, which then runs to the MN-100, where
it then goes to the base computer and to another room.
Just yesterday, the computer in the other room won't
connect to the internet. The base computer (and the one
I'm using right now) can connect to the internet. I have
rebooted both computers, reviewed both connections,
checked options under internet tools, reviewed Network
Neighborhood but nothing seems to work. Why will one
computer, connected the exact same way as another, connect
to the internet, but not the other one?

Any help would be appreciated.