System sounds set to zero/off

[MikeNY]

This used to happened to me on the Nexus but every once in a while the water drop sound goes away, typing sound goes away etc and I have to keep going to the volume controls and slide the volume back up again. I even dowloaded Audio Manager like I did on the Nexus and still this happens a few hours later. Anyone know why and how to prevent it from going silent?

Thanks.