I would suggest you to keep your wordpress version updated.
Have you done anything with .htaccess file, I am sure you will have to deal with that if you are getting ISE – 500
why don’t you use the default function of wordpress to call the tags on your page rather than themes function.
<p><?php the_tags(); ?></p>
let me know if this works for you !!!
I would love to help you in this if you can send me the url of the installation domain.
