A friend asked me to look at her guitar because the high E string buzzes when played open. It does not buzz when fretted in any position. The "E" sustains, but has a "zzzzzzzzzzz" reminiscent of a sitar.
I haven't tried anything yet, but my best guess is that the nut slot for that string is cut so the string is not resting on the edge nearest the fretboard. Perhaps it is resting part way back, and therefore vibrating against the nut itself.
However, along with making sure the nuts on the tuner posts are tight, are there any other likely culprits I should check before getting out my little saw?