Mandatory profiles are roaming profiles that are not updated when the user logs off.
Even if the users change their desktop settings while logged on, the changes are not saved, and they will see the same settings the next time they log on. Windows® 98, Windows 2000, and Windows XP clients support the loading of mandatory profiles.
To change a Windows 2000 or Windows XP profile to be mandatory, open the folder on the logon server where the profile is stored and change the extension of Ntuser.dat from .dat to .man.
To prevent the user from altering their profile in any fashion, you also need to ensure the share is configured as read-only, and the appropriate integrated file system directory permissions are set.