Magento : Use Categories Path for Product URLs configuration doesn’t work

I have a store with a few categories. Most products in the store are in 2-3 categories.
I want to have only one url for each product – domain.com/product_name.html.
I don't want to have products URLs with the category path in them.

I set “Use Categories Path for Product URLs” to "NO", but when I reindex the Catalog URL Rewrites it creates for each product one regular url (domain.com/product_name.html) and one for each category path (domain.com/category_path/product_name.html).

I've deleted all the product URL rewrites that contain category path, but when I reindex the Catalog URL Rewrites it creates them again.

Isn’t the “Use Categories Path for Product URLs” configuration should prevent this? Am I missing something?

I'm using Magento ver. 1.7.0.0

Thanks