Why does GarageBand cut off the recording when I hit the D note?

Today I started noticing that whenever I hit the D note, during recording Garageband cuts out and does not record that note. Is it the soundboard? The mic? The cable? I tried reinstalling Garageband. Still does it. I changed the mic and audio cable. Still does it. I tried Quicktime audio, that seemed to work. But why does GB cuts off the recording when I hit the D note?

[Re-Titled by Moderator]