Domain DNS issues HELP

Try to make this short.

Created a new domain, with primary PDC running AD, installed DNS server looks fine.

Domain name corp.corporate.

I use my router to specify my DNS severs as WAN primary and PDC secondary.

Add a computer from the desktop takes forever to attach to the domain, but eventually works. Then reboot, login as domain admin and add user from the domian.

FAILS trust relationship?

Change the domain to the netbios name corpcoprate, takes forever. Reboot add user from the netbios domain name, works fine.

REAL kicker.

Got to remote office attached via VPN add DNS corp.corprate works immediately. Add user works immediately.

Any ideas would be appreciated!