Skewed instruments in music

[zajurai]

This occasionally happens to me sometimes, I think it has a small chance of starting whenever I zone, but I don't know what causes it for sure.

My issue is that sometimes, one instrument in the music shifts higher, anywhere between half an octave to 3-4 octaves. It's usually the violin, which makes the Felwithe, Kelethin, merchant themes and death theme sound nightmarish and unsettling. It happens to the horn sometimes, which screws up the character select and combat themes.

It's not the biggest issue - I'm not even sure if I want it fixed, it makes things more interesting - but I at least want to know what causes it.