Redirect loop results in products_id=0

Wow, I sure have no idea what is causing this redirect loop.
I've been searching for an answer all day.

When I put in an address for a product that no longer exists.
Example:
http://www.fashionpatterns.com/index.php?main_page=product_info&products_id=69
This will redirect to:
http://www.fashionpatterns.com/index.php?main_page=product_info&products_id=0

But this page does not exist. It redirects again to the same page... and gets into a loop.
"the server is redirecting the request for this address in a way that will never complete"

If I eliminate everything from my htaccess file, the problem persists.
I can't seem to track down where this is coming from.

I also cannot add a rewrite to the htaccess that will get around this.
Example:

RewriteEngine On 
RewriteRule ^index\.php\?main_page=product_info\&products_id=69$ http://www.fashionpatterns.com/index.php?main_page=page_not_found [R=301,NC,L]

This will do nothing. Still gets the same loop.
This leads me to believe that it's coming from somewhere in my files or configuration.
I just have no idea where or how.

I really need some help.
Thank you.
Jason A.

Understandably you are a long time user of ZC based on your join date to the forum; however, there are several questions in the posting tips (viewable from scrolling up after selecting reply) that would help others help you.

If you wouldn't mind taking a moment to answer as many of those and anything else that you think might help inaddition to them, perhaps the ball can get rolling.

Wow, that was an amazingly quick stroke of luck.
After all day of running into a brick wall,
discovered that I had an outdated file in this folder:
includes\modules\pages\product_info
deleted: header_php_review.php
Everything works fine now!

patternman:

Wow, that was an amazingly quick stroke of luck.
After all day of running into a brick wall,
discovered that I had an outdated file in this folder:
includes\modules\pages\product_info
deleted: header_php_review.php
Everything works fine now!

Side note, there are many folders that will load every file that ends in .php. In the future, if a file is being renamed for testing, suggest some other extension. If the file is to remain on the server an extended period of time, then the extension should not be .old or .bak (pci compliance). Ultimately files that are not necessary for the operation of the site should be removed at the earliest convenience...

Glad you found that though!!! Now off to more zenning! :)