setting admin rights?

[TheGrOgStEr]

I've got a home network and I want to be able to shut down a computer from another computer on the network.
shutdown -i is the command to use I know but there are two problems that occur.
#1. I can't find any computers when I click on "browse" in the GUI because a popup box says "The Directory Service is currently unavailable".
I'm wondering how to make it available.
#2. when I bypass the gui and just type in the whole command in cmd, it says "access is denied".
I know I need to set admin rights on my computer, but I don't know how to do that for networks. the network works perfectly, file sharing, internet sharing, "net send"ing and so on. I just don't have admin rights from one computer to another on the network.

and incase someone asks, all my user accounts are admin accounts.

[arckane]

all your user accounts must be admin on all PC's, and they must all have passwords. A null passworded account cannot remotely execute commands, this is a security feature.

Rather than using the version of shutdown built into Windows, you may have much more luck with the one called PSShutdown which you can find in the free pstools.zip file available on www.sysinternals.com. This is a remote admin pack for Windows with commands such as process listing, process killing, service management, etc. As I've already said, it's completely free and the tools are excellent.

[essexman]

need a password on at least 1 account. u also need to add the remote desktop users group on the account with a password.

[TheGrOgStEr]

I tried pstools but it always says Access Denied..

and I just can seem to get remote desktop working to allow one computer to even select the other to allow a remote connection.

i'm wondering if I have to be in a domain with the other computer, rather then just a workgroup.