What OS are you running on the server? Table service or quick service?
I use taskkill all the time.. If you have XP you should have taskkill..
Open a command prompt
Example
Taskkill /s TERM1 /f /im iberqs.exe
or if you don't know the computer name for the terminals type
arp -a
this will tell you all the computers connected to your server and the ip addresses. If for example terminal 1 is 192.168.0.1 and you are using quick service
Taskkill /s 192.168.0.1 /f /im iberqs.exe
if you are using table service
Taskkill /s 192.168.0.1 /f /im iber.exe
the /f means force, i pretty much use it by default.
you could also use VNC, good chance its on your terminals.
You could also map one of the terminals with net use, path to \\term1\c:\documents and settings\all users\start menu\programs\startup
then you could break the iber.bat shortcut or the RAL shortcut and then restart the computers with the shutdown /m command.
I can think of a few more ways but I just noticed this thread is a week old.. lol I assume by now it is fixed..