This is kind of my issue as well...except the AT&T rep that I spoke to had no idea there were any issues and kept telling me there were no issues. She sent me into the AT&T store and by the time I got there they had suspended pre-orders there as well.
*I have a non-iphone (mine was stolen so got a crap phone to hold me over until the new phones came out)
*I HAD a FAN number and took it off yesterday hoping it would solve the problems (obviously it didn't).
The guy at the AT&T store also said there is nothing wrong with my account but gee...still can't preorder on apple.com.
I guess I am going to go early on launch day to AT&T because I am scared to waste my time at Apple and have them run into issues.
UGH!
I'd be mad if I were you! Get your iPhone stolen and then make plans to get a new one and now you can't because of this ANNOYING error! I'm getting it too. You're not alone. I hope they fix this.