Yep, the problem is that you added that items field. Find:
PHP Code:
mysql_query("INSERT INTO users VALUES ('', '$username', '$pass1','$email','free','0')");
Replace With:
PHP Code:
mysql_query("INSERT INTO users VALUES ('', '$username', '$pass1','$email','free','0','0')");
Every time you add a field to the users table you also have to make a space for that field in the register2.php file. This is one of the reasons I discourage mods modifying existing tables and encourage them to create new tables of their own. :)
Those users will need to re-register as they were never inserted into the users table.