Advance login system (v1.5) [updated!]

This code that was writen to show how to make an log-in system on your site (but you can also use it as an template). But no just that. It also features a security agains breaking the password through brute force (= trying a lot of passwords). And different access levens, an easy to use admin interface. You can even make user into admins, delete there accounts and activate there account's (the normally recieves an code by email to activate the acount). updated(1/1/2003): changed config.inc into config.php for increased security. updated(2/1/2003): added comments, fixed some very small bugs. updated(7/1/2003): added userlevels, simplyfied the security header for member-only pages. updated(11/1/2003): fixed some bugs, made the admin screen "htmlproof", changed the activationnumber into an activationcode. updated(22/1/2003) fixed bugs (again, code is never perfect) added version.txt added more comments updated(3/3/2003) fixed the notices appearing if the pages are accessed directly added documentation.html more configuration in config.php updated(15-6-2003) added remember me function added more validation added tripod support added a PM system MORE INFO + LIVE DEMO: HTTP://UTIMER.PCPLAYGROUND.COM/ALS/