i.e., using command [. I'll do a search, click on a page, find its not what I want and when I got back instead of giving me the search results I get a blank page. I then have to hit reload to get the results back. In more extreme cases I'll do the search, click a link and suddenly the browser will think there's no page to go back to.
I think this behavior has cropped up sometime in the past few months.