the program plays notes 2 semitones higher than the correct note

This afternoon, my Musescore program started doing something very strange: the audio plays notes that are two semitones higher than the correct note. For example, the score has a Db. If I hit that note (the notation reads "Db" at the bottom of the page as it should), I hear an Eb. If I hit Bb, I hear a C. And so forth. I checked a couple other of my scores, and they do the same thing. I even uninstalled the program and reinstalled it, but the problem persists.

I cut out all but the first four measures of one of these scores and attached it below.