The sleep issue with the Hi8 Pro in android seems to be the WI-FI. Download a wi-fi widget and turn wifi off before you press the sleep button and it wakes up 100% of the time (at least on my tablet). If it hangs up for you, reboot to android and if your wifi is ON upon reboot, it means you forgot to turn it off (happened to me a few times). Just remember to turn off wi-fi before pressing the sleep button.