When I click on Safai's back button, instead of displaying the page I had just visited, Safari frequently displays an outdated version of the page. Common examples are wish lists at Amazon or Ikea, or watch lists at eBay. For example, I'll click on an item on the current list -- but when I try to go "back," I see auctions that have ended days ago. Typically, the outdated pages are 1-5 days old. It's especially frustrating when I use the swipe gesture to go back, because I can see the correct page being revealed as I swipe, only to be replaced by an incorrect page when I'm done. Clearing the cache just delays the problem's next onset. I'm using Safari 5.1 with Lion. I've never noticed this problem under prior versions -- although internet searches suggest people have been experiencing this issue since Safari 3. Is there some setting I'm missing?