We've gotten a few emails from people who have registered but who cannot log-in immediately afterwards.

When registering your account, immediately after entering your registration details and clicking the 'Submit' button, a message is displayed confirming that your information was sent, and that an 'Activation 'email has been sent to your registered email address.

You MUST click the link contained in that 'Activation' email, or your account will never be authorized.

I know it seems like a pain, but this is one of very few ways to prevent spammers, bots, and hackers from abusing the site.