A would need a little more information. When you say the OS is frozen can you still ping the machine from a remote machine?
If so then you can open a remote dos window and run the shutdown -r to restart that pc. You can also remote desktop in and shut it down. You can keep outlook running on that machine with a rule that when a specific email comes from you it should run a batch job – with the shutdown -r command in it.
Send an email reboot your machine… Let me know if you need more help.