Just replace the files with the ones in this .zip.  
Do NOT run install.php or upgrade.php again.

08/28/06 - Manual instructions

- Find:

unset($check_url);

after it add:

$output = "";
if(empty($useruid)) {
	$adminloggedin = 0;
	$loggedin = 0;
	$level = 0;
}
if(ini_get('register_globals')) {
	foreach($_SESSION as $k => $v) {
		unset($GLOBALS[$k]);
	}
}

If you updated earlier in the week part of this will already be there.  
I'm just listing it here again for those who requested a clarification.

- In user.php find this section around line 78:

				if($passwd[level] != 0) {
					$_SESSION['adminloggedin'] = 1;
					$_SESSION['email'] = $passwd['email'];
					$_SESSION['admincats'] = $passwd['categories'];
			     	}

Directly beneath it add:

				else {
					$_SESSION['adminloggedin'] = 0;
				}
