One of our customers had a Windows 2003 Server, that once the April 2011 Windows Updates were installed, after rebooting, it would take almost 2 hours to log into the console. Also, some of the service could not be started, stopped or changed. We could also not RDP into the server, but we could still connect the the SQL Server 2000 databases and the file shares were still accessible. Since this server was approaching 4 years, the customer decided to go ahead and replace the server.
The new Dell Server arrived and we also upgraded their SQL 2000 to SQL Server 2008 R2. We wanted to have the name of the new server to be the name of the old server, so we first renamed the old server, then we rebooted to apply the change. Surprisingly, after we gave the old server a new name, it booted right up like normal and let us log into the console as normal without the previous 2 hour delay. All of the services started normally and we could now RDP into the server.
Now we did not rename the old server back to the original name to see if the hang at login would still occur, but my guess is that it would not hang and that it would log in normally.
UPDATE: We had this happen again on a different Win2003 Server. We disconnected the network cable, logged into the server. Renamed the server and rebooted. Booted normally and was able to log into the server. Renamed the server back to the original name and rebooted. Server now boots normally and does not hang.
Something must getting reset or rebound when you change the name of a server to make this issue get resolved.
Hope that this information may help you if you find yourself stuck in this situation.