[Warning] wp-db.php on line 500

This search:
http://wordpress.org/search/open_basedir+restriction+in+effect?forums=1

found, among others, this:
http://wordpress.org/support/topic/145475?replies=3 which points to this http://webomania.wordpress.com/2006/10/12/open_basedir-restriction-in-effect-error/

Please, if you have a moment, tell us how you fixed it?

Ok I’m looking further down in the function calls.

line 499 of /wp-includes/wp-db.php

$log_file = @ini_get('error_log');
                if ( !empty($log_file) && ('syslog' != $log_file) && !is_writable($log_file) )
                        $log_error = false;

Change to:

if ( !empty($log_file) && ('syslog' != $log_file) && !is_writable($log_file) )
                        $log_error = false;