Screen Rendering On (Final) Product Page When Additional Images

I have set thumbnails to 250 by 250 as the default with 2 columns (if if you prefer 2 items per row) for product display.

This looks good to me and causes no problems - that is until I reach the final screen for a product where I have 3 additional images.

Now cscart insists on displaying the 3 images on the same row - rather than just 2 per row. This means that - the scroll bars appear - and the right hand side of the screen is not immediately visile.

Is there any setting that I can change to sort this problem.