In 2.2.3 and 2.2.4 if you have the private messaging module installed, and try to register I recieve this message:
You don't have permission to access /modules/profile/register.php on this server.
If I uninstall the private messaging module everything is fine. I have had this problem for a while but just figured out how to stop it.
PHP - 4.3.11
MYSQL - 4.0.25 - STANDARD