Inconsistency loading default profile

We run an NT40 domain and have added WindowsXP Pro machines. Though a default user has been set up in NETLOGON in both PDC and BDC, the WindowsXP machines will not consistently load the profile when new users log in. The profile was actually created using Windows2000, and there is no problem with those machines. There is no option to create a network default user profile for an NT domain from XP, since such requires active directory to work. Need a solution to provide consistent loading of the default profile.