Disable shutdown and loopback GPO issue

Hi,

I have 3 computers at school which I want left on all the time (i.e. disable shutdown). I acchieved this through using gpo, by configuring 3 options:
user config: admin templates: start menu: remove and prevent access to shutdown command
AND
computer config: window settings: security settings: local policies: shutdown
AND
computer config: admin templates: system/group policy: User group policy loopback processing mode (replace).

It works fine, and shutdown options are disabled. However, I now notice that on these 3 machines only, the pupil profile system is not working- ie. it doesn't grab the redirected start menu, my documents, favourites etc (but the pupil account does grab the correct mandatory profile). If you log on as a pupil on the other machines as the same pupil account, it works fine. I've rebooted all computers several times.

It's a win2k network with xp pro sp2 clients.

Could it be the loopback mode? Should this be set to merge only, not replace? I don't really understand loopback, but any help would be much appreciated!

Thanks yet again :)

Sorry to solve my own post, but merge was the right option with loopback.

Anyway, for future surfers, this thread might be useful....