This morning my husband's phone started playing a tone incessantly. There are no notifications, and as soon as you touch the notifications bar at the top the tone stops. At random intervals during the day it starts up again. The tone is not one that is in the ring tone list (it is two annoying buzzes). It isn't his calendar, alarm clock, or anything else we can find. Anyone else experienced this? Is it a virus? He is running Lookout.