If your website is centered in the browser window, and some of your pages are much shorter than others, you may have noticed pages jumping from left to right by about 10 or so pixels when navigating between pages. This is caused by the browser's scroll bars appearing on longer pages, and disappearing on smaller pages.
This is expected behavior and shouldn't be seen as a problem. Also, any “solutions” only really create new problems in other
browsers, particularly those in Windows, so don't recommend using them. Remember that, as the creator of the website, you'll be more aware of it happening. Take a look at other centered websites (including Apple's) and you'll see that the same thing happens there.