Using a recent git version of org-mode (release_7.5.209.g1a687) with a fairly recent emacs-snapshot (20110408-1, a package from the debian emacs-snapshot ppa, but running under ubuntu maverick), I'm having a really terrible calendar bug -- not sure if it comes from org or from emacs, but reporting here in case anyone else has seen it. Attempts to insert a timestamped schedule or deadline using C-c C-s or C-c C-d bring up an EMPTY buffer called Calendar, while REPLACING THE CONTENTS of the active buffer with the text of a calendar. I had a near-catastrophic moment where I killed what I thought was a calendar buffer, but then ended up erasing my main reference file for all my org notes. Has anyone seen this behaviour? And do you think it comes form org or calendar?