Hi tomerg3.
I can't post a URL to a product page on my site because currently to temporarily solve the error, I've disable AJAX on my site, therefore the products can be ordered.
However, if you need to have, here is my product's website. http://www.petmarket.com.sg
I'm using 1.4.3 and it was an upgrade.
If i were to enable AJAX, customer the AJAX function CAN be successful only if customer click on "Add to cart" on featured products in the first place.
If a customer were to click on any "Add to cart" of one of the products listed in the featured product, the AJAX works fine for all "Add to cart" clicked on individual product page. Even the removal of product works!
HOWEVER, if a customer were to enter my site and click on the categories and choose a product, then the clicking of "Add to cart" will result in the technical error mentioned in this thread.
Hope that helps! Looking forward to hear from you!