Are you using the shutdown feature that came with the computer? The reason I ask is because I sometimes have had issues with remote shutdowns from command prompt. Another question; do you already have a network drive mapped prior to trying to shutdown your remote computer? If not that may be your problem. That error comes back to me when I don't have a network drive mapped. One day I was doing some looking around on Microsoft website and found this:
http://www.microsoft.com/technet/sys...g/PsTools.mspx
This comes with more than just a shutdown feature 'psshutdown' but other things as well.
When/if you choose to download this, but it in a very easy to reach place. like "C:\PsTools". Reason being is because you will have to go through that path to access that file, its not like the original shutdown command, you cant just type it in and it execute. What the 'psshutdown' does is allow you to take command from your workstation. The usual line of commands I use is: "psshutdown \\COMPUTER NAME -u USER NAME -k -t xx (where xx is a set amout of time)". It will prompt you with a password requirement, and you will enter it blank. It will NOT come up with stars or anything of the sort, the cursor will not move, it will look as if you weren't typing anything.
I personally enjoy this tool. It hasn't given me any problems, and you don't have to map to the remote computer to use this either. That's why they incorporated the user/password tool.
Good luck, I hope this works for you as well as it does me.