drupal hangs with avatar module enabled and selected in the right side bar ( when php is not installed with gd library )

I have installed avatar module and went to administer -> blocks and select avatar to display in the right side bar.
Then it gave me the following error

Fatal error: Call to undefined function: imagecreatetruecolor() in /www/docs/drupal/modules/avatar_gallery/avatar_gallery.module on line 348

and then drupal doesn't get loaded again.
the drupal site gets displayed only after deleting the avatar module from the modules directory of drupal installation.

OS: Mac OS X 10.4.2
Drupal 5.0
Configuration file Protected
Database schema Up to date
File system Writable (public download method)
GD library Not installed
MySQL database 4.1.13a
PHP 4.3.11 Unicode library PHP Mbstring Extension
Web server Apache/1.3.33 (Darwin) mod_ssl/2.8.24 OpenSSL/0.9.7i PHP/4.3.11