I've checked in Chrome as well as the two browsers you've mentioned and all seems ok in all three. I don't have access to IE unfortunately. Could you take a screenshot of what you're seeing and let us know which browsers are effected please so we can look into further.
Usually when the sidebars move under the content, its either due to the padding/margins of a section within the 'page template' area being edited using css, which causes them to be pushed outside of available area and below. But in saying that there are other things that can affect it, if you're seeing this on IE, please make sure 'compatibility mode' is not active within the browser.