Computer name change

Running XP PRof. on a Windows 2000 network includes DHCP, DNS, WINS and Exchange 2000.
How do I change the computer name, I get the following error:
“The following error occurred attempting to rename the computer “computername”
Multiple connections to server or shared resource bt the same user, using more then one user name, are not allowed. Discconect all previous connections to the server resource and try again”
any suggesting ?