Disable lock screen in XP

From: Steffen (heise_at_umich.edu)
Date: 08/27/03 

Date: 27 Aug 2003 08:24:25 -0700

I'm trying to prevent students in the lab from locking the computer. I
set the policy in AD so that the button Lock Computer after
CTRL+ALT+Delete is greyed out. I disabled the windows key so that
Win+L doesn't work anymore. But rundll32.exe
user32.dll,LockWorkStation is still working. Any idea on how to
prevent this?

    Thanks,
        Steffen