Several times since the latest "upgrade" I've had the same post repeatedly appear when I do "View New Posts" even though I've already clicked "Mark All Forums Read....". Right now it's happening with the Capitalism thread and Orat's last post, which has been presented as new about five times already. Am I the only one? Is this a known bug in the current IPB version?

It's not a bug, it's an indication someone new has voted in the poll (this only happens with polls).