Did you run the liveupdate first?
ASUS released a new BIOS/Software ver. 4.03 on OCT 3rd and Software ME400C ver. 4.0 on OCT 17th.
These are apparantly required before upgrading to Win 8.1.
The upgrade installed smoothly on mine and the performance is significantly improved.
However, there is a problem..... after pressing the power button when in standby, the screen remains black and needs 1-2 presses then an error msg that the the display driver crashed/stopped responding. It recovers fine and does not appear to have any other negative effect.
Anybody else experiencing this or similar?