OK, I've got to be doing something stupid that I can't figure out. I found an old thread about sound quality, tried changing the ini as described there--no difference.
If I run buddamamev91, mamev80 or nonamemamev83--I get the same result each time--galaga88 runs fine (framerate varies in each case and is almost too slow with v91) but the sound is a bit garbled in galaga, pacman and mspacman (those are the only ones I've really tested lately). Doesn't matter if I launch from commandline or Mamewah.
Any ideas why each version would have the same problems, when all those games played fine a few days ago?

What'd I screw up?
I'm running a PIII, 1ghz w/ 512mb ram w/XP home.