If a Windows Vista-based Dynamic Host Configuration Protocol (DHCP) client computer is restarted and if the DHCP Server service is not available, the client will not maintain a valid lease. Therefore, you cannot access some network resources.
The computer loses the IP address that was assigned to it by the DHCP server even though the default gateway is available. Instead, an Automatic Private IP Addressing (APIPA) address, such as 172.16.0.0, is assigned to the client computer. Or, if the adapter was assigned an IP address by using the Alternative Configuration tab for the adapter, the adapter will us
e this address.
Click Start, type regedit in the Start Search box, and then press ENTER
Locate and then right-click the following registry subkey
Right-click DontPingGateway, and then click Modify.
In the Value Data box, type 1, and then click OK.
This procedure forces the client to keep its DHCP IP address, even if a DHCP server is not available. If you use the Alternate Configuration tab to modify the IP address for an adapter, this IP address is assigned to the adapter.