Silencer/vibrate not working

[ethan]

I've been having a problem where when my phone is on silent or vibrate, it sometimes turns itself off and sometimes just makes sounds anyway. Any idea how I can fix this?

 

[Melon Bread]

Are You Using Stock Android, And Is Rooted or Not Rooted?

 

[ethan]

Yes, it is stock and it is not rooted. I have a task killer running and auto killing, but I have checked the exclusions multiple times for anything that would be affecting it and can find nothing.