Aggregator problem - posting an old story always at the top, can't get rid of it??? Sure this issue is local

A random old RSS item posts at the top of the feed everytime I update, regardless if I remove everything, reset the feed address, etc. It always says it has been posted so-and-so seconds ago, like probably the time that I loaded the feed - weird. Don't think its the source of the feed because it shows up fine in firefox bookmarks; tried other feeds with the aggregator and theyre fine - is there something stuck in the database somehow??? Any help greatly appreciated.