Taxes check box on products page disappears


In the Admin section, I have a strange problem in the products page. While adding a new product I tick the ‘taxes’ check-box. But it disappears. But that works fine and calculates the tax properly. If I need to edit any product, then I must check the taxes box again. It applies the tax but check box remains unchecked.

I have installed another test site in the same domain and that works perfectly. How can I solve the problem? Any file / folder permissions to be changed???