If you are unable to start the dhcp client service and receive an access denied message, it’s due to the network service account not having the permissions. Follow the below instructions to resolve:

1) Click start
2) Click run
3) Type regedit (please be careful when editing the registry – Always take a backup)
4) Navigate to \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dhcp\Paramaters
5) Right click the parameters folder/key and click permissions
6) Check that the network service is visible and has full control permissions
7) If the network service account does not exisit, add and grant full control
8.) Start the dhcp client service