If you'll entertain 3 guesses...
1. When you go to print, and the Excel print window appears, asking for number of copies, etc., there is also a dropdown menu that also asks which printer to use.
Try reselecting your printer. (I'm guessing this preference is corrupt.) You may even have to trash all Excel preferences.
2. Verify fonts in Font Book.
3. Do an Excel custom (re)install.
Sorry for the .5assed guesses, but at least they shouldn't hurt.
