I went through all of the various driver update procedures (using various OEM drivers and the most recent 2-20-2013 Asus drivers). After updating drivers using the intial driver update guide, I couldn't get sleep mode initiated by the power button to wake after a short period of time. I have never been able to get LiveUpdate to connect (Cannot connect to server error message) so I used a manual update to the 2-20-2013 Asus driver updates. I was able to get consistent sleep mode from the power button for maybe a few hours, but never could stay in sleep mode overnight. If left in sleep mode overnight, I would need to hold the power button for several seconds, then again to get the familiar buzz to get a restart. In another thread (T810C - driver_power_state_failure), I found something interesting. I checked my driver settings in Device Manager/Network Adaptors/Broadcom Wireless/Power Management. Both options on my Vivotab were intially checked - 1) "Allow the computer to turn off this device to save power" AND 2) "Allow this device to wake the computer." I read the warning message about enabling the second options, so I decided to UNCHECK the second option. I used the tablet at various times last evening, using the power button to go into sleep mode. I left it in sleep mode overnight, and this was the first time ever that I was ever able to wake it up overnight without going through a restart routine. Granted, this was only a data point of 1, but I will try again this week. Others may want to do the same and try it out. Please post your results (worked overnight, or didn't work overnight). By the way, my serial number begins with CCOKA, in case this means anything.