ISPs and MXes

When a new user authenticates to pop/imap server, before it gets auto-created in drupal I'm see the following php errors:

* warning: array_keys() [function.array-keys]: The first argument should be an array in /www/drupal-5.7/modules/user/user.module on line 380.
* warning: array_fill() [function.array-fill]: Number of elements must be positive in /www/drupal-5.7/modules/user/user.module on line 381.
* warning: implode() [function.implode]: Invalid arguments passed in /www/drupal-5.7/modules/user/user.module on line 381.
* user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1 query: SELECT DISTINCT(p.perm) FROM role r INNER JOIN permission p ON p.rid = r.rid WHERE r.rid IN () in /www/drupal-5.7/includes/database.mysql.inc on line 172.

The user also will see an error indicating a bad user/pw, however the user is created and logged in. I tracked this problem to the following code in user.module:

  if (!isset($perm[$account->uid])){

Oddly, when I change the code and add an additional check, the error is avoided and user created and logged in:

//  if (!isset($perm[$account->uid]) && $account->uid <> null) {