Thanks, I'll look back at the tech data on the files and see if any of these suggestions might apply. I guess what has been the biggest puzzle is that the first 3 songs I uploaded to the web don't have playback problems but the fourth one does. They were all recorded by the same program on the same day w/o any change in specs and then converted a few days later to the MP3 in a batch. I forgot in the original post that on the fourth one I did a little "massaging" with another program (added a very light reverb effect) and uploaded the song after applying the effect. Perhaps, the saved version in MP3 after the effect was applied was set at a different bit rate.
Thanks again for responding