My first suspicion (other than a bug in Finder) would be that you have e.g. an Input Manager or Contextual Menu Item (or other system hack such as APE) installed that is interfering with the normal working of the finder. Check the equivalently named folders in your ~/Library/ and /Library/ folders to see if you have anything in them and if so, remove them to e.g. the desktop, restart your Mac, to disable them and try again.