Possible Glitch w/ Pedal

Ugh.....I've had too many issues with Musescore lately. I wrote a piece with a sustained pedal for 10 bars at the beginning. The first few times I played it, it was fine but all of a sudden it would become a lot slower, distorted and crackly in the middle of the pedal hold. Is this because of the long pedal hold, or is it a different issue? Thank you?