[jeiyuu]

This problem seems to be hit and miss based on each device. Speculations are primarily dealing with custom 6.1 roms, and today time-outs. I have remedied this problem on my device by disabling today time-out and changing the power setting to never sleep. I am running ghettofreeryder's 6.15 - it may be something simpler for you if you are runing the stock rom.