How to prevent scrollbar from repositioning web page?

Issue

I have a website with center-aligned DIV. Now, some pages need scrolling, some don't. When I move from one type to another, the appearance of a scrollbar moves the page a few pixels to the side. Is there any way to avoid this without explicitly showing the scrollbars on each page?

Solution

overflow-y:scroll is correct, but you should use it with the html tag, not body or else you get a double scrollbar in IE 7
So the correct css would be:

html {
  overflow-y: scroll;
}

Answered By - Ruben