when I register as a User

the system email sends a password. when I go back to the site to login I enter my user name and the password the system sent, and the next page comes up saying “you don’t have sufficient permission to enter this site”, but when I click the back arrow I am signed in. This is a bugger, because the user would think they are not allowed to enter after registration.

Also, since the password is sent by the system how would I redirect the user at the first login to the my account change settings (password screen) automatically to the my account page?

One more thing, the emails are set up to send the registration info (name and password) and welcome email to the new user, but the registration is not sending. The welcome email however is sent fine.
Any idea??
Thanx very much