There's a freeze-screen hotkey? Do you mean keyboard shortcuts? There's
no freeze-screen keyboard shortcut either.
Anyway, go to windows Help and Support, and paste-in: Windows keyboard
shortcuts overview. You can see them here too:
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/keys_general.mspx
See if that info helps.
Also, go to
http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx
and get Tweak UI (download link in the right column). After installing
and running, look in the Explorer section.
Lots of things are annoying until you understand them. In particular
programs, the possibilities are endless. For example, in Word, if you
accidentally hit the Insert key, you'll go into the insert mode, and
you may not know that hitting the key again will get you out of it.
How many students do you have, and how many machines?