Rebooted the server last night and the screen would not get past Applying computer settings… There seemed to be very light disk activity. I discovered that if I rebooted in Safe Mode with Networking and re-enabled the IPv6 on my Local Area Connection, the system would boot normally. I had turned it off earlier but had not rebooted since that change.

Steps:

1. Right click on my network connection in the system tray and select Open Network and Sharing Center
2. Display the Local Area Connection Status
3. Click Properties and make sure Internet Protocol Version 6 (TCP/IPv6) is checked
4. Quit everything and reboot

The only other potential factor was the server was behind a NAT; it could communicate with the local network but could not reach the outside world due to a misconfiguration in the firewall.