Problem with subcategory images in Internet Explorer, Chrome, Opera..

[EUnet]

I have not assigned any images for subcategories. In browsers such as Internet Explorer, Chrome, Opera (I'm using the latest versions of these browsers).. there is a empty box next to each subcategory name like there is an error in showing subcategory images.

 

Everything looks OK in Mozilla Firefox, I do not have any images assigned for subcategories and Mozzila Firefox does not show empty boxes like other browsers, it only displays the names of categories as it should be.

 

I am attaching images how it looks like in different browsers:

1. as seen through Internet Explorer

2. as seen through Opera

3. as seen through Mozilla Firefox

 

How to solve so that empty boxes do not appear in Internet Explorer, Chrome, Opera..?

I am not using any additional template other than the one basic PrestaShop template that comes with the installation files.