This one is a tough one without actually being there. Can you provide screenshots of your network and sharing center and adapter list? (If you still want to try and solve this problem, it seems that others have given up.)
Is this a desktop? or laptop? Do other computers connect fine? How far away are you from the router? Wired or wireless? What kind of router is it?
Is this a desktop? or laptop? Do other computers connect fine? How far away are you from the router? Wired or wireless? What kind of router is it?