When I upload pictures via Upload Attachment, I get a popup window that says "The upload is currently in progress" and it doesn't go away. The original webpage autodirects me to posting.php?mode=post&f=8&sid=361e992b72f5c285fb2f7878fe
(which I removed a few characters from, in case it links to anything), and Google Chrome doesn't do anything else with it.
Am I doing it wrong? I've tried in Firefox, too, and got the same error.