Playback completely pauses during rests

...then continues from where it left off often making it sound like there's a grace note.

It happens during normal playback, adding / selecting notes, and in rendering.

Here is an example: http://www.queatz.com/files/b4m2.ogg
As you can hear it very much disrupts the flow of the music.

I noticed, as you will hear in the attached test.zip, that it only happens with some instruments and does not happen every time, like the very first note in the attached zip's ogg.
In the attachment there is a horn which does this pause while the strings do not.

Simple way to test:
1) New score, 1 Flute
2) Start adding notes

That alone already gives me artifacts.

Musescore 0-9-6 revision 3400
Linux using ALSA and Portaudio.