I don't know what character that is but it's obviously not a bullet. It doesn't happen in Firefox, so I don't think this is a font or OS problem, it seems to be specific to IE. Does anyone know how to fix this? It's only cosmetic but it is really annoying.
After considerable effort I figured this out. Somehow, Wingdings got deleted from my fonts folder. When I reinstalled it the bullets started appearing as they should.
(My concern now is... how did Wingdings get deleted from my computer? I don't remember doing anything to delete it. Everything else on my computer seems fine. A full virus scan turned up nothing, although it doesn't seem likely a virus would delete Wingdings and leave everything else untouched...)