I haven't figured out what action causes it to happen yet, but I have a bunch
of comment boxes that look like they're disappearing. They're not actually
going away; the red indicator is still there, and when I mouse-over, one of
two things happens: either the comment box has been shrunk until only half
(or less) of the comment is visible, or it has been shrunk out of sight
entirely, so only the arrow is visible.

If I go to Edit Comment, I can re-enlarge the box back to normal size, and
everything is fine.

The problem described at
http://www.eggheadcafe.com/software/...disappear.aspx seems to be the same, if that helps.