This means a computer on your network has the same name as yours. So, Windows cannot assign an IP or DNS address for conflicting names.....Change the name of your PC by going: System Properties>Computer Name>Change and change your computer name. That should do the trick.
Restart and you'll resolve this issue. If it didn't, repair the connection by going to Start>Network Connection, click on your LAN controllers, go to details and click repairs.................... it will renew the IP address.