The best way to remotely reboot a Windows system is:
1. Open Windows PowerShell ISE
2. Find the "Restart-Computer" command.
3. Click "Show Details"
4. Now enter in the information for the computer you want to reboot. Generally it is a good idea to check "Force". "ComputerName" can be an IP. If the computer is on a domain, make sure to set the credentials field to a "MYDOMAIN\myuser" format.
5. Click "Run"
Now this will show you the PowerShell command that is generated by ISE. It should prompt you for your password for the given user if all goes well.
You can actually use this to make your own .ps script.
Extras:
If you get an error about "System shutdown is in progress" - wait a bit. It may be Windows Update. If it still fails, download SysInternals Suite and try this command:
pskill -u joey \\192.168.0.11 winlogin
pskill is a SysInternals Suite command, so make sure you're in that directory.
