We recently got a new iMac. The old one is getting kicked down to the kids. I set up parental controls and it seems to work fairly well. I am having one serious problem though.
If I check "Only allow selected applications", if I log in under one of the kid's accounts, I get a blank desktop. No menu bar, no dock, nothing. I have to power the iMac down to be able to log back in to my account.
It's an older white iMac, 2Ghz Intel Core Duo, upgraded to 10.5.7.