XPS 15: random wake up from sleep problem

Anyone else having trouble with their L501 staying asleep?
I unchecked any "allow this device to wake up computer"
and similar options in Windows 7 (64 bit ultimate) device
manager; but still the system wakes up randomly
from sleep. Powercfg -lastwake tells me it was the
power button, even though the button was not pressed...

 

I've been having this issue also, am not sure exactly what is waking it up but it's annoying.

 

I solved my problem at the expense of some functionality:
Go to power options / advanced settings and change
"lid close" action to "do nothing" for both on battery
and AC power.

This essentially disables the lid sensor: my laptop no longer goes
to sleep automatically when I close the lid; but it also doesn't wake up
from sleep when I open the lid (only pushing the power button wakes it up).
Most importantly, it now stays asleep once in sleep mode (until
I press the power button, of course).

So the problem seems to be a calibration problem with the lid sensor:
it appears the sensor is over-sensitive and would send occasional
lid-open signals randomly. At any rate, that's my semi-wild guess
diagnosis of the issue...