Relentless -
What you posted will essentially include the href twice, and have no class tag for the link.

<a href="http://www.samplewebsite.com/index.php?main_page=index&cPath=28">' . zen_href_link(FILENAME_DEFAULT, $box_categories_array[$i]['path']) . '">

ht tp://ww w.samplewebsite.com/index.php?main_page=index&cPath=28

is exactly what

zen_href_link(FILENAME_DEFAULT, $box_categories_array[$i]['path'])

evaluates to, so you would get in execution

<a href="http://www.samplewebsite.com/index.php?main_page=index&cPath=28">http://www.samplewebsite.com/index.php?main_page=index&cPath=28">