Also mysterious notes are sounding during the rests!  

Is this a score you typed in yourself or something you imported through MIDI?

Are you using MIDI playback or Aria/VST style instruments?

I typed it myself.  I'm using Garritan.

How did you enter the tie?

Try deleting the tie, clicking on the eighth note, and then pressing the T key.

(If another instrument in your arrangement sounds the C (or E, depending on clef) while the voice you show is tied to the sixteenth, it may sound as if the sixteenth is re-striking. Just a far-fetched, obvious thought.)

Deborah, we really can only speculate, since this forum doesn't allow posting Finale files. If you like, send it to me at wawoodman at aol dot com. I'll take a look!