Recently purchased Asus Transformer Book T100 with 64BD HDD. it works quite nice.
However after some time noticed that it no longer reacts to rotation and all options for it are gone from Windows 8 charm menu too.
Fix is quite easy. Open your Device Manager locate InvenSense Sensor Collection. It should have exclamation mark, right click on it, select “Disable” then Right click it again and “Enable” it again.
Now rotation should work right away.
If you notice that this start to happen again and again, try to disable Windows 8 “Fast Boot” option, that should fix this permanently.