background problem in IE7

[pilandok]

Guys,

Been using the CMSMS for several months now and it works flawlessly. My ordeal begins when our students upgraded to IE7. 

Here is the problem:
My site background is black and the size of the page is 740pixels (centered), other browsers have no problem displaying the setup, but *some* workstations running IE7 have problems. The  background is black but not  complete, there is a white background around 50pixels in size on the left and right side of the page.

Just want to get an idea where abd what files  to modify. Been searching for solution for a couple of days now.

Thanks