Hi,
This seems to be a communication issue. Try the following,
1) In the Ghost Console go to to Tools --> Options --> Server Timeout. Check the time allocated for Timeout. The ideal value is 20 minutes. If its low increase it.
2) This issue can also be caused due to lack of updated NIC drivers in the boot package. When the client is in Pre-OS try to ping it from the server. If you are not getting a reply you need to add Vista NIC drivers of the boot package. We are adding Vista drivers because Windows PE is based on Vista.
Hope this helps.
Regards,
Prasanna