I’ve recently come across a few Windows 2003 servers that were unable to start the DHCP Client service, instead an “Error 5: Access is denied.” message would appear.  Now I’d kind of inherited responsibility of these servers so I wasn’t really aware of their history.

Although the servers we’re using a DHCP assigned address, they were being moved to a new site and network range and as dynamic DNS registration relies on the DHCP Client service its failure to start was making my life harder than it needed to be.

A quick Google brought me to this Microsoft Support article (http://support.microsoft.com/kb/895149) which seemed to describe the problem well.  However upon applying the fix the service still wouldn’t start and gave the same “Error 5: Access is denied.” message. 

At this point I loaded up Process Monitor (http://technet.microsoft.com/en-us/sysinternals/bb896645) and started monitoring the registry while I attempted to start the service.  A bit of digging later and I noted an ACCESS DENIED result when trying to open the key “HKLM\System\CurrentControlSet\Services\Dhcp\Parameters” as shown below

Access Denied Result
Process Monitor Screen Shot

So I granted the Network Service Full control over the key and retried starting the service, SUCCESS!!

If you come across the same issue give Process Monitor a go and keep an eye out for the ACCESS DENIED results when attempting to start the service.  This should point you in the right direction.

Hope you find this useful!

n3ilb