Problem in Access this computer from network in Local secuity settings

we are having a strange problem. In one of our windows 2003 server in our network ..Access this computer from network in Local security settings become blank freaquently .so network users is not able to access the computer..every time we login the server locally and add corresponding users to “access this computer from networ settings”..

please send me the solution for this issue

bala

bramad2@lsu.edu