The sideboxes show up correctly in FF and too big in IE....

the background image i'm using is 180px wide, and the sideboxes are set at 180px via admin control panel...in FF it shows up right, but IE makes it too big and then it pushes out the whole right side of the site by a few pixels. IE shows the sideboxes correctly when it is set at 175px, which makes no sense when the background image is 180px...

I can't figure out how to fix this

P.S. THIS ONLY HAPPENS when in a category such as "TOPS"