separate part play back

Whenever I create separate parts away from the original score, my computer tells me that it can not be read. this happens every time I try to make large separate parts with more than five voices, however when there is only one or two voices it seems to work perfectly fine. Maybe it is my laptop, but its not even one year old. I love this program and would like to be able to hear separate parts again. Thank you!

GIT commit: f51dc11