The "Next" google reader bookmarklet is a bookmark button you put in your bookmark bar, and when you click on it, it redirects you to the next unread item in you google reader list, but not in google reader. It shows you the original page.(If you go to Google Reader settings > goodies, you'll find it.)
When using the next bookmarklet for many times in a row, sometimes with 2-3 seconds of interval to skip uninteresting stuff, sometimes I want to go back to the previous, and when I click the browser back button, it often skips some 2-5 pages and goes to a very previous one, and not the one I was expecting.
If I use the backspace instead of the back icon, it skips it aswell, and if I right-click the back icon, it doesn't show the history for the one I was looking for.
It happens on normal, beta and dev versions of chrome.
In Firefox it does not skip.