WordPress MU

In order to hide potentially offensive comments from users I have installed the Adminimize and Role-manager plugins. Using RM I've removed the capability to edit comments and using Adminimize I've hidden the Comment section in the LHS menu- but comments still show up in the Dashboard.

I tried removing the comments element from the dashboard and disabling the 'Screen Options' in Adminimize - but to no avail. My only solution now is to turn off the Dashboard entirely for that user.

Now comments are totally hidden, but the default screen after logging in is the profile screen (not a major issue, but not ideal) and students who are users on more than one blog can't access any other unless they change their default blog and then and then click 'Settings >> Admin Bar'. A bit of a chew on for my poor Year 7 (11 year old) bloggers...

Why not use this simple spam plugin here:
http://tantannoodles.com/toolkit/spam-filter/

Toss it in mu-plugins, after editing it to have as many of the words you don't want them to see. It'll can those comments immediately.

By no means a bad idea. My concern is largely that someone will find a way to bypass it with a particular phrase and I have made assurances to parents that their little darlings will be protected.

simply remove the comments from the template, so that no one can comments ... although it's a dirty idea :D

"users must be logged in to comment"

but is it gonna suddenly help the propose? rather then this membership upon invitation is batter.
http://wpmudevorg.wordpress.com/project/secure-invitations

How did you get adminimize to work with WPMU?