Can't get online when open web browser.

Can't get online when open web browser. The messages that come up are 'local area network unplugged', and 'think vantage access connections status: disconnected'. I have checked the wires and cords repeatedly and all are connected and OK. I have tried to diagnosed the problem through windows but with no luck. Everything else about the computer is working OK. I just can't get online and the connections are Ok. I wonder if there is something wrong inside the computer?  My computer is an R61 Thinkpad, bought new Feb 08
Regards Kathy