share file access from win2003 domain controler

Active directory server 192.168.1.10, lot of share folders in that machine(192.168.1.10), all other XP machines should access the share folder of 192.168.1.10 machines, permissions already set, XP users also can access the share folder when they are login to their particular domain user name.
when they are working it asks the password when they are opening that server. if they logoff and login again it will work without asking password.
what is this problem.