I was trying to install the network policy service in 2008 to setup a Radius server. The policy wouldn't install properly, so I uninstalled and reinstalled with the same results. After poking around I tried to manually start the remote access service. It said that the dependancy service wouldn't start. I went through each dependency and found that everything started except for Telephony. I tried to start it and it would start and then stop right away.
I went into the properties and looked at who was logging in to start this service. It said it was the Network service. For some reason the rights for Network were not enough to start it. I could have looked everywhere, but instead I changed it to the local system account and it started up. Now the rest of the services started and the policies installed. Success!