The additional images may be working, but with the site breaking somewhere on the page you will not know for sure until you find the problems causing the break.

You should have error debug running (if you are using version 1.3.9h). Take a look in the cache folder on your server to see what the error logs may be telling you.

If there is no error log - visit your images. I've had several clients
who uploaded huge images (600dpi !) and that breaks the cart sometimes too.

Tina