i have a problem with the layout of my sub category pages

when viewing it via firefox it only shows 1 column and yet in admin i have set it to allow upto 5 have tried default of aswell
here what i meen http://www.modchipfitters.com/index....index&cPath=20

when i switch to the classic template all displays as normal
has anyone any idea which file has the settings in and what might be set wrong?
btw dont try looking at the site in IE as i am in the middle of setting up a conditional ccs page for IE to try and solve a few problems i am having with the different ways that ie and ff handle the css