2 min. wait before network login works

I just finished setting up an AD/OD "magic triangle" configuration. Clients (10.4.11 PPC) authenticate with an AD server (Win2K3) , then auto-mount home directories hosted via AFP by an OD server (10.5.4 Server PPC). The trouble is, if you boot up a client you have to wait two minutes after the login window appears before you can login as an AD user! I've timed it several times and it's very consistent. Local users can login immediately. If I wait the two minutes I can login as an AD user, then logout, then log back in again, etc. It's just after the initial boot-up that you have to wait the two minutes. Does Directory Services start up after the login window appears? I've seen this behavior in pure OD environments, but I've never investigated it in depth. Anyone know anything about this delay? Thanks! P.S. I don't think this issue has anything to do with AD or OD specifically, but because it has to do with network logins and because this is my first stab at setting up a mixed AD/OD environment, I figured I'd post it in here.