Add to the cart goes to Page cannot be found

[nettrak]

Ok i have a strange problem.

- I'm using zencart 1.5
- I installed a theme. Although I've gone back to the classic theme and problem persists
- I have the module Simple SEO installed yet i've turned it off and still have same problem.

Problem: On my product info page when you click "add to the cart" it goes to my page not found page.

Interesting Scenario though: When you click on a Buy Now button it adds the product to the cart with no problem.

Examples of the problem: http://www.dresshaute.com/shop-by-co...ck/black-dress

IF you go there and click "Add This To my Cart" you will see my issue.

However if you go here: http://www.dresshaute.com/products_all

and click on a "Buy Now" button it works as how I want the add to the cart button should work.

Does anyone know what I am doing wrong or what code needs to be examined or changed. I really don't want to reinstall everything and start from scratch but i know I may have to.

Thanks!