Error when trying to use

Same here

Fatal error: Call to undefined function: str_ireplace() in /clientdata/www/domainname/sites/default/modules/advuser/advuser_filters.inc on line 422

Drupal 5.9
PHP Version 4.4.8

maybe something like this would help for PHP 4 systems - http://bytes.com/forum/thread467075.html

As a test I added the following code to advuser_filters.inc around line 10

// quick fix for no str_ireplace on PHP 4 platforms - http://bytes.com/forum/thread467075.html
if (!function_exists('str_ireplace')) {
	function str_ireplace($needle, $str, $haystack) {
		return preg_replace("/$needle/i", $str, $haystack);
	}
}

and then I could perform the necessary filtering, that is the module worked as expected.

Thanks for your quick fix. Worked for me!