To fix this remove the reservation, renew the IP address of the client laptop and then re-create the reservation on the DHCP server, this will fix the problem.
ipconfig /release
ipconfig /renew
DHCP Address Allocation Issues
If you have a laptop that suddenly cannot get an IP address from the Windows based DHCP Server and in the Windows event log you get entrys referring to the DHCP server could not renew the lease 0.0.0.0 and that the DHCP server has issued a DHCPNACK status to the client, then you have a corrupt reservation in the DHCP database.
To fix this remove the reservation, renew the IP address of the client laptop and then re-create the reservation on the DHCP server, this will fix the problem.
To fix this remove the reservation, renew the IP address of the client laptop and then re-create the reservation on the DHCP server, this will fix the problem.