Cindea

Morning, I have added 3 songs to my slideshow and the 2nd song crackles during playback. I know the song doesn't crackle when listening on the computer or my iPod etc. Is there a setting I am missing maybe? Setting I should change? The format for all songs added/imported is .m4a is there a recommended format that is better? Copyright isn't an issue. I paid yet aside from that, the others work so I am baffled. This is for my daughter's wedding so it's crucial I resolve, I can find another song but ....the song in question is "Then They Do, Trace Adkins it's much older than the other 2 I have chosen. Could that be why? Much appreciate any help. Thanks for your time Cindea~