Can some one help me to solve the problem on my Local Area Network (Internet)?

[MreG]

I have a computer of which connects to the Internet through another one, but this computer is failing to get connected, the connection pop on and off yet the network cable is inserted in well. but at times it shows a Red cross on a Local Area Network icon. and at times it shows a Yellow triangular object which has an exclamation mark in the middle of that triangular object, and it happens on the Local Area Connection Icon, on the far corner of my computer's task bar.

and when i restart the connection inorder to establish a full connectivity by clicking on Repair button, it can't finish repairing, it states that " this connection has limited or no connectivity, you might not be able to access the Internet or some other network resources"
What could be the problem?

Please can some one help me out?

[MikeH]

make sure your firewall is not blocking the connection