Registration Failed and Now Network Setup Assistant Starts Up When I Boot

I installed 10.5 and everything went fairly smoothly. However, when my computer finally rebooted and asked for me to register, the registration process failed --- it kept trying to "connect" without any success. So, I closed the Setup Assitant and rebooted. When my computer once again booted up, it did not ask me to register; instead, it opened the Network Setup Assistant. Now, every time I boot, the Network Setup Assistant starts up. I therefore have two questions:

(1) Is my copy of 10.5 registered? Is there a way to check? Or a way to re-register it?

(2) How do I get Network Setup Assistant to stop opening up when I boot my computer?

Thanks for your help.