This always happens with Google properties when I'm using Safari. It doesn't happen on Twitter, Flickr, Facebook, Hotmail, Yahoo, etc. Just Google. The problem surfaced with the Safari 4 beta, and has persisted since. It happens whether I have extensions enabled or not, and even if I change cookies from "Block Third Parties" to "Accept Always" (I've left it at Always for weeks now, doesn't help.)Grrrr.