If you're using firefox you can get a plugin called imgLikeOpera to block images (which then puts little squares on your screen where the images should be... which you can then click... unfortunately you'll have to guess which square belongs to which box) or I saw another edit boxes link somewhere (maybe in create trades?) that works...
the problem seems to be connected to a bug I posted awhile back about Farfetch'd and breeder cards (at least the error causing both bugs is the same)...
I can't change my default box (at least not from the edit boxes link on my boxes page)... the images don't show up... I used my 'inspect element' plugin and the pictures/links are there but not showing... when I try to load the image from the url I can see in the source I get the same error message from the Farfetch'd bug I posted previously. This seems to be the important line from that error page:
Warning: imagecreatefrompng() [function.imagecreatefrompng]: '
http://www.thepikaclub.co.uk/adopt/images/box/.png' is not a valid PNG file in /home/pikachu/public_html/adopt/boximg.php on line 13