A – DHCP is NOT the problem.
B – Conflicting credentials is the problem.
C – Did you mean to say that you went to “Active Directory – Users and Computers” and in the list of computers you deleted the named instance of the retired computer? The computer that failed (motherboard/hard drive)? Or both?
D – Presuming Windows XP Pro on the laptop, login as the local administrator on the laptop. Does not need to to be connected to the network. Right click ‘My Computer’ and choose properties. On the ‘Computer Name’ tab change it to workgroup not domain. You may get a request for domain credentials, or an error message that the domain controller could not be contacted. Proceed, and it will switch to workgroup. This will require a restart. Log back in as local administrator and go to the same tab, but this time change the name to something unique and not related to either previous incarnation. This will require a restart. Attach a network cable and log back in as local administrator, go to the same tab and join the domain. You will be prompted for an account/password set with the permissions to perform the join (members of the ‘Account Operators’ group). It may take one to five minutes for the ‘Welcome to xxx domain’ to appear, depending on network speed and the number of computers in the domain.
And it is time to restart again.
E – Forcing a name change on a disconnected computer is the only dependable way to clear identity crisis for computers in a domain.