I had a client very upset because the windows 8.1 update killed her Sonicmaster (s500c) touchscreen. As it turns out; The problem is caused by the lid switch… the Power4Gear software which powers Asus power setting defaults to sleep mode when the lid is shut. You can adjust this profile to remove this function i.e. "do nothing" but this still turns off the touchscreen. Work around; The solution is to shut the lid again and this tricks the computer into thinking it is waking up from sleep mode and turns the touchscreen back on. To be clear, I don't agree with everything in windows 8.1 but a fair go may convince me of it's worth.