This is from another forum (HP that uses DS for HP's RDP) See if any applies to you.
This error can occur for a few different reasons.
1) Spanning-Tree is enabled on your Cisco switch and Port-Fast is not enabled on the Host ports. You need to enable Port-Fast on all ports that have PXE clients attached. This disables loop detection on those ports, but it is a common practice on host ports.
2) DHCP is not available or not Authorized (MS AD). In your case, this does not seem to be the case.
3) If multiple NICs are in your PXE client server, ensure you are plugged into the corret NIC. Some NICs tell you when the cable is not connected, others don't.
4) DHCP is on another network segment and there is no DHCP proxy agent or helper address (on the router).
Source is http://h30499.www3.hp.com/t5/ITRC-ProLiant-deployment/PXE-E51-quot-No-DHCP-or-DHCP-Proxy-Offers-received-quot-error/td-p/3057862#.UL-11YOijyo