The previous category link was incompatible with my version of OSCommerce. (Most recent with patches). I have added an alternate method into the package.

In catalog/includes/products_next_previous.php

FIND
$prev_next_in = PREV_NEXT_CAT . ' ' . ($category_name_row['categories_name']);
CHANGE TO:
$prev_next_in = PREV_NEXT_CAT . ' <a style="text-decoration: underline" href="' . tep_href_link(FILENAME_DEFAULT, "cPath=$current_category_id") . '">' . ($category_name_row['categories_name']). '</u></b>';


THIS IS A COMPLETE PACKAGE

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