Blue screen when push "Lock Screen" cmd via ARD
In a lab of 30 Intel Macs (Mac OS X 10.4.10), when the teacher pushes the command to "Lock Screen" to the class, the machines all freeze up and display a blue screen. (Much like the ever so popular Windows BSOD!) From that point you lose control and the computer is completely frozen up, then requiring a restart.
However, if the teacher pushes the "Lock" command individually one computer at a time it works fine. And after the command has successfully worked on a one-by-one basis, you can then push the Lock or unlock command to all 30 and it will work. So the glitch appears only to happen after the computer initially boots, and you try a large group.
Any suggestions on how to fix this glitch. It is a real hassle to remotely lock the machines one at a time every morning.
iMac, Mac OS X (10.4.10)