This has been one of the long-standing complaints about the new website - the screen will 'jump' back to an earlier position when you are scrolling through a long or photo-heavy item page.  VERY annoying.  Also annoying; it has been pronounced "fixed" by the website guys more often than I can count.  It is NOT fixed.  To be fair, though, it is a very quirky error that seems to vary quite a bit depending on what machine, operating system, and browser you are using.  They will test it extensively, find that they are not having that problem, and we all assume that the bug has disappeared.  

A customer recently offered his observation that the problem is much more or less noticeable depending on how he is browsing the site: specifically, if he is scrolling down the page and maintaining a gentle pressure on the wheel of the mouse (like many of us do), it jumps often.  If he scrolls to where he wants to be and then takes his finger completely off of the mouse wheel, it jumps much less. 

Eventually, we will probably end up programming something that will allow you, the individual user, to choose whether or not the site is actively checking whether the item is available or sold.  That live, real-time data is actually at the heart of the problem.  I don't want to give that up, since it is key to the site's operation, but we may allow you to temporarily disable that function for your own browsing experience if it is causing a problem.