I have a very weird thing happening with Exchnage 2003 SP2 and AD. Recently some users are not showing in the GAL. Some of these users have been in AD for years. I notice that if I run ADSI edit and look at one of the users, the showinaddressbook attribute is not set and then when I look again seconds later it is set.
This replicates in the GAL with the user being there one second and gone the next. I can create new users that work OK.