DHCP error in event log

Hello all,

I'm getting this error message on a mate's computer. Everytime that it occurs the computer immediately goes into sleep mode and you have to undergo a hard re boot to turn it back on.

Event ID: 1002

Type: Error

The IP address lease 10.0.0.1 for the Network Card with network address xxxxxx has been denied by the DHCP server 10.0.0.138 (The DHCP Server sent a DHCPNACK message).

Any ideas would be greatly appreciated. I've tried ipconfig /release and then ipconfig /renew but that didn't work.