Over in this thread in the forums, 'gowrann' was having a problem with NetInfo Manager. Any time they tried to save a change in NetInfo Manager, the program replied: "NetInfo write failed! (Operation succeeded)", and the changes were not saved.
'CharlesS' correctly deduced that the problem was the setuid flag on the NetInfo Manager application itself. To correct the problem, open a terminal and type:
% cd /Applications/UtilitiesIf you're interested in reading more, the thread has details (courtesy of 'MervTormel') on exactly what the setuid bit is and why it's important to have it correctly set for NetInfo Manager.
% sudo chmod 4775 NetInfo\ Manager.app/Contents/MacOS/NetInfo\ Manager
Mac OS X Hints