Fatal error: Unsupported operand types in /var/www/vhosts/drupal/includes/common.inc on line 1275

I have a relatively new installation of Drupal 6 with a multi-site setup. One site is working fine but the other gives me the error: Fatal error: Unsupported operand types in /var/www/vhosts/drupal/includes/common.inc on line 1275

This occurs whenever I attempt to post new content or update existing content. The content is created and/or the changes are typically made even though the error is received.

I've read through a lot of the posts in regards to this issue but haven't found any that are specific to this area or that I believe resolve the issue. I found http://drupal.org/node/147990 however, the section of code ending on line 1275 does not include static $cache; so I'm not sure how to apply it to this situation.

function url($path = NULL, $options = array()) {
// Merge in defaults.
$options += array(
'fragment' => '',
'query' => '',
'absolute' => FALSE,
'alias' => FALSE,
'prefix' => ''
);

Any help would be most appreciated.