i had the same problem, using my laptop as an htpc. lid closed it would not resume aka wake from sleep unless im opened lid and touched the internal keyboard or power switch.
workaround. i think almost all new laptops have/use a magnetic sleep sensor switch, if not then it probably use a mechanical switch.
if it uses a mechanical switch it should be easy to figure out how to disable it. for now these instructions follow a magnetic switch/sensor.
find schematics of your particular laptop, you need to locate the sleep sensor, usually somewhere above keyboard.
alternate method, using a paperclip find where the magnet is located on the lcd trim/bezel, in doing so you will roughly know where the sleep sensor is located when lid is closed.
switch on my gateway nv75s , aka acer 7560g, has a magnetic lid sleep sensor.
magnet on mine is in the lower part of lcd trim/bezel.
sensor that senses the magnet is just above my speaker.
i taped down a thin piece of metal where sensor is located, and voila, no more sleep/wake issues using usb mouse or wol in sleep mode. the thin piece of metal sheilds/blocks sensor from activating and thin enough to not hamper lid when closed. you could also add thicker rubber pads to lcd cover to give extra height when lid is closed.
laptop now wakes in sleep mode via usb or wol
perfect for a htpc that uses an external monitor and is set to primary display.
you could also remove magnet from lcd lid or sensor depending if its a pia to get to.