Being asked to register on my own blog

I can go to my blog one time and I’ll be automatically logged in, and then if I navigate away from the page and come back later, the “Register” link is on the right side. At other times, the “register” link is there when I first go there. If I click it, it takes me to a login screen with my user name and email already filled out. Then, all I have to do is click the “Login” link underneath and it takes me right to the blog as being logged in. Anyone know why it’s not logging me in automatically every time I go to my site? BTW, it was doing that in WP 2.07 and now in 2.1. I even tried adding my domain to the trusted sites to accept cookies from, didn’t help.