i had the iconia w510 without the keyboard and did not have this problem but i exchanged it for the one that came with the keyboard and now every time he system goes to sleep after periods of inactivity, pressing the power button does not wake up the machine. pressing on the windows button does a "buzzing" action but the screen is still black. the only way to get the machine working again is to hold the power button for 10 seconds to shut down and restarting the PC. I have done all the windows udate but it does not fix the problem. Any ideas? do i have a defective tablet or is this a problem with the model that comes with the keyboard?