Urgent help needed on a live site

hI THERE

i have my site up and running since last 4 years

because of design reasons i have a few html buttons that let users add a product with a single click

inside that button, i have a code that passes several atributes and do the trick

<td colspan="6">
			<form method="post" action="index.php?main_page=product_info&cPath=0/&products_id=181/&action=add_product" >

<input type="hidden" value="1" name="cart_quantity" />

<input type="hidden" value="181" name="products_id" />

<input type="hidden" value="RELEVANT DATA FOR ME" name="id[txt_9]" />

<INPUT TYPE="IMAGE" SRC="./images/buttonmadebyme.gif"></form>

i use that code one millon times in several parts of my site and my blog and my fb ( all of them did the trick of carrying the user to the zc cart with that product added succesfully )

ok, suddenly that code don´t work anymore

i tryed everything and almost lost my mind, and finally found that now, ( and I dont know why ) the text atribute must be passed this way:

<input type="hidden" value="RELEVANT DATA FOR ME" name="id[TEXT_PREFIX9]" />

why** id[txt_9] **don´t work anymore and now it has to be id[TEXT_PREFIX9] ?

Please explain me why did it happen?

I didn´t changed anything today, and during this morning everything went fine, and suddenly this miraclous code don´t work anymore

I have placed millons of pieces of code in different part of my site so I need to know how to fix it , ( please dont provide alternative ideas because its almost impossible for me to change every place that code is )

Hope my english is not too bad to explain this odd mess

my data is the following

SO del Servidor: Linux 2.6.32.8-grsec-2.1.14-modsign-xeon-64 Base de Datos: MySQL 5.1.53-log

Servidor HTTP: Apache
Versión PHP: 5.2.17 (Zend: 2.2.0) TITLE_PHP_MEMORY_LIMIT 90M TITLE_PHP_SAFE_MODE Off

Zen Cart 1.3.8a
Patch: 1::