we used to do this in our computer class. we would go into the ms-dos command prompt and type some command and be able to send messages to any computer in the lab in the same windows that the computer gives you error messages in.What is the ms-dos command for sending messages to other computers on a network?
If the messenger service is turned on, and not blocked by a firewall this will do it:
net send COMPUTER_NAME "This is a message"
Of course change COMPUTER_NAME to the name of the computer to send the message to.