IP Address Conflict but Can't Release or Renw

I put a new (used) Vista laptop on a workgroup and it always gets "An error occurred while renewing the interface Local Area Connection:  The DHCP client has obtained an IP address that is already in use on the network. The local interface will be disabled until the DHCP client can obtain a new address".  The problem is that since the local interface is disabled, I can't release or renew the address.  Plus, I can't tell what the exact address is that is causing the conflict.  If I put in a fixed address it works fine, but goes back to having a conflicting IP address once it set to automatically receive and IP.  Since this is a laptop that will regularly be taken offsite, I can't leave it in a fixed IP state.  

This workgroup uses Server 2008 as the file server, but, as I said, this is a workgroup and not a domain.  The DHCP server assigned to the NIC is the modem/router IP, not the server, and that is also the DHCP address the other computers are automatically assigned.  Because this is a new site I'm not yet fully familiar with, I'm not sure if the server is set to also be the DHCP server.

This laptop has a fresh installation of Windows.  It was reinstalled at my shop, which uses a 10.0.0.x addressing scheme and we had no trouble picking up an auto IP address there before I brought it to the client site.

Does anyone have any suggestions how to get this machine to pick up a non-conflicting IP address?