Internet Browse Issue

A user is running a Windows XP Pro computer in a domain environment.
Approx. 30-60 minutes after logging on, the user will be unable to browse
Internet websites via Internet Explorer, Firefox, etc. However, the user is
able to ping those addresses successfully.

At the same time, the following error appears in the System Event Log
........


Event Type: Error
Event Source: NetBT
Event Category: None
Event ID: 4321
Date: 3/11/2010
Time: 5:38:48 PM
User: N/A
Computer: COMPUTERNAME
Description:
The name "DOMAINNAME :1d" could not be registered on the Interface with
IP address 192.168.2.114. The machine with the IP address 192.168.2.114 did
not allow the name to be claimed by this machine.

For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.
Data:



Note: The 192.168.2.114 address is the wired NIC that is on the internal
domain network. A wireless card is also present, this is connected to a
separate network that only has Internet access.


Please help!