old MCX Settings showing up!

I have a 10.6.8 pure environment - 1 server, 20 macs in a standalone lan.

In the past, I set curfews, and they worked. At some point, I turned them off, and for the most part, that worked (no more curfews). But sometimes - very randomly it seems, the curfews show up on the logon screen (the red "do not enter" sign next to the user in the list).

I have since turned on then off again the setting, both at the user level, and the computer group level - and it still sometimes happens.

I tried logging on as an admin user with "option" key - per http://support.apple.com/kb/HT3540, I do get the picker, but NEVER see the option to "refresh preferences". As an admin - how can this NOT show up??

Any other suggestions?