I've been renaming the headers on my side boxes and things were working well until I started renaming my Document Categories and EZ Pages headers. I edited these files:
includes/language/english/extra_definitions/document_general.php
includes/language/english/extra_definitions/ez_pages_definitions.php

After renaming the headers, I got this message:
Fatal error: Call to a member function on a non-object in /home/cobrapla/public_html/store/includes/classes/category_tree.php on line 68

The main page loaded fine until I clicked on a link. After that every page had the above message where the Document and EZ Page side boxes should be.

I didn't touch the category_tree.php file prior to this occurring. I checked that particular file, and I didn't see any codes on line 68. Anyone have any thoughts on how to fix this?