your GD version states 2.0.34 compatible but does not report the actual version.
the error occurring is:
Call to undefined function imagecreatetruecolor()
the imagecreatetruecolor function is defined by the GD library, it should be fine in GD version 2.01 and above. You should contact your host to determine why that function is not included in your PHP version.
you can disable the security code by commenting the following two lines:
$WAFV_Errors .= WAValidateLE(((isset($_POST["Security_question"]))?strtolower($_POST["Security_question"]):"") . "",((isset($_SESSION["random_answer"]))?strtolower($_SESSION["random_answer"]):"") . "",true,5);
var sprytextfield3 = new Spry.Widget.ValidationTextField("sprytextfield3", "none", {validateOn:["blur"], minChars:<?php echo $WAGLOBAL_Captcha_Characters; ?>, maxChars:<?php echo $WAGLOBAL_Captcha_Characters; ?>});