For a Windows 2000 machine perform the following:

   1. Right click on 'My Network Places' and select Properties
   2. Right click on 'Local Area Connection' and select Properties
   3. Select 'Internet Protocol (TCP/IP)' and click Properties
   4. Select 'Obtain an IP address automatically" (and repeat for DNS) 
      and click OK

For Windows XP perform the following: 

   1. Select your Start button --> Control Panel--> Network Connections.
   2. Right click your Lan connection and select properties.
   3. Go to the networking tab.
   4. Make sure that Internet Protocol (TCP/IP) is checked and highlighted, 
      then click properties.
   5. In this screen, make sure that the "Obtain an IP address automatically"
      radio button is selected.
      The "Obtain DNS server address automatically" should also be dotted .