noise added on OGG playback

I have a problem playing some OGG files with pygame.mixer.music.play():
When I pass a start position that's not zero into this function, on
playback of some files (not all), I get noise mixed in with the
playback of the file for as long as that file continues to play.  The
noise resembles loud crackle from a vinyl record.

The WAV files were originally 16-bit/44.1kHz, I converted to OGG using
the same consistent settings in Audacity, and I have called
pygame.mixer.init(44100).  All the files sound fine played back from a
zero start position, and some even sound fine with a non-zero start
position, but others consistently have this problem with a non-zero
start position.

I've considered that it might have to do with whether the music at the
specified start position is at a zero crossing (all nearby samples at
least close to zero amplitude), but no amount of modification of the
file at the chosen time point was able to remove the noise.  Plus, it
seems like the worst that ought to happen is that you would hear an
isolated clipping sound at the beginning of the file (if the
zero-crossing issue were it).

Can anyone enlighten me somewhat on this?  Has anyone had a similar experience?

Thank you,
David Tweet.