Servers Stuck on Grey screen on reboot
Servers had to be power cycled to recover the server.
Microsoft analyzed the crash dump for us and came up with a private fix. However before we could test the fix we resolved the issue by updating the version of RDP clients on our workstations and limiting the use of the /console switch.
The article below describes something similar to what we had a recommends the use of latest RDP client for server management and using the /admin switch
http://support.citrix.com/article/CTX120644