compatibility

I have the windows 7 version of musescore and have created a score that i can send to members of my choir so that they can use the playback functions to help with part learning. I have had complete success with choir members that also have windows 7 but one lady has xp. She seems to be able to view the score but the sound is scrambled. Is there a way to make them compatible or is it more likely that she is doing something wrong? Many thanks for any help! Caz