Unable to create new user

[Ajia]

My current Mantis is 1.0.5.
It worked on Mac OS X 10.4 Server well. After my company installed Mac OS 10.5 on the server, Mantis cannot create/update new user account any more.
Mac OS X 10.5 Server's configuration is: Apache/2.2.6 (Unix) mod_ssl/2.2.6 OpenSSL/0.9.7l PHP/5.2.4
I use server's pre-installed PHP and MySQL. After restore Mantis 1.0.5 and its database, I tried to create a new user account, and got below problem.

On the client side, browser gives "Safari can’t open the page “http://.../mantis/manage_user_update.php” because the server unexpectedly dropped the connection, which sometimes occurs when the server is busy."
On the server side, the console gives: "[notice] child pid 14213 exit signal Bus error (10)".

I still can create new project without problem.

Did anybody else encounter this problem? I am thinking to upgrade to Mantis 1.1.1, don't know it will help or not?

[Ajia]

I still have this problem with our system.
perhaps I can ask this question: what kind of reason could cause mantis "create/update user" problem? Or work around?

[Ajia]

Found a solution:

from config_inc.php file, turn check MX record off ==>
$g_check_mx_record = OFF;