Rob: I once had a roll with about 3 frames that looked like they were full of
flyspecks. I ran it through Vuescan to see if it would remove the "dust." I
wasn't dust. It was in the emulsion, probably done in the devolempent process.
I then used the "remove blemish" tool in Photo Suite 3 and it remedied the
situation My guess is that your problem is in the emulsion and is not dust.