I purchased and installed Leopard 10.5.6 on my older G5 tower, upgrading from 10.3 or 10.4, I don't remember which. Regardless, the install went fine, but upon restart it is asking me to login as a guest, myself (name), or other. I have never had to login when starting up and have no idea what password it is asking for. I've tried two support articles from Apple, neither of which worked. (http://support.apple.com/kb/TS1543 and http://support.apple.com/kb/TS1400?viewlocale=en_US) I tried to sign up for Apple Support, just to be able to talk to someone, but you must enter your S/N, and when I do it says it's invalid, even though I re-typed it several times. Frustrating to say the least. Thoughts? I'm really stuck here, any help is greatly appreciated. Thanks.