Frankly it turned into a hunt for what it could be and a slow removal of items from the machine until it started working again. In my case it was some USB devices (external drives.) I have yet to find any specific item but let me share a few tricks.
1. Disable the sound card. It's a server, we don't need a sound card.
2. Remove all USB connected things you can. It's a repeating find here.
3. Ditch any server/service you can.
4. BEWARE if you went over 1GB RAM. Microsoft has documentation on this. I'll let you find it.
I have two Compaq/HP-Proliant 360 servers. Both servers fail to complete a reboot when Microsoft pushes down updates that require a reboot.
The reboot fails on the screen "Shutting down system" - and the systems keep working, and can be accessed (slowly) by my users. The keyboard does nothing at the servers - I can't bring up Task Manager to try to complete the roboot that way.
I have several other servers with about the same configuration that reboot fine by themselves.
The only "foreign" (not part of the OS and not part of the HP package that comes with the servers) that is common to these servers and not on any other servers is GOTOMYPC... a remote access tool. I've contacted GoToMyPC's technical support and they can't find any references to it causing this problem. They suggested contacting MS support (HA!) Unfortunately - I can't really try running them without GoToMyPC - since these are production servers that I need to use G2MyPC to access when I'm on the road. I also can't reboot them for diagnostics in-hours and the boss limited my out-of-hours work.
I'm stumped - any one have any ideas. NO error messages are logged. I've tried using remote management and going in and stopping the GoToMyPC service - and the reboot still doesn't continue.