Unable to Save - Error on theme.inc

I was unable to open the browse window, so I moved the disknode folder to the core/modules directory and it works fine now.

But when I try to save a disknode or any node (say story with disknode as attachment), I get an error related to the theme:

Fatal error: Cannot use string offset as an array in X:\XXXXXX\xcorex\includes\theme.inc on line 552

The node is actually saved, and the attached file info is saved correctly. I can edit the node and see all the info (node/##/edit).

The error comes up when the node is shown (node/##)

This is a multisite config running Drupal 5.1 on a Windows 2003 server with XAMPP.

Line 552 of theme.inc is:

552 function theme_links($links, $attributes = array('class' => 'links')) {
553  $output = '';

I tried using garland or bluemarine, but still got the same error.
I have nicemenus running, by the way, but as I mentioned, the node is properly saved. The error comes up when displaying the node.