My wife's TiBook (running the latest Tiger) suddenly started doing something weird: after a shutdown and restart, many of her Address Book records have changed so that one person's name now has someone else's e-mail address or title. (Phone numbers do not appear to have changed.) So then, when she addresses a note to, say, Cher, Mail actually sends it to Sonny. There seems to be no pattern to which addressees get substituted.
This happened to her once before, in Panther I believe (she's running 10.4.2 now), and went away after a reinstall. I just the other day ran MainMenu and cleaned out her system thoroughly. Any ideas what's causing this or how to fix it? Maybe delete Mail or Addressbook plist? Help!