Basically the question says it all. I have an Asus N55SF laptop with a fresh install of Windows 7 ultimate (with all the updates) and no Asus pre-installed software (eg: Asus Power management tools... all drivers and chipset updates are installed) nor other power management tools installed, nor other software that can potentially override the settings. Also, have an external monitor plugged via the lateral HDMI port.
Power settings, for both battery and plugged-in, are set so that the laptop will never power off disks/monitor, sleep nor hibernate. That is both for idle time and laptop lid's closing.
I'd like to use the external monitor only, with the laptop always closed but apparently it's not possible. Whenever I close the lid, I get maybe up to 15-20 minutes worth of usage then it hibernates (or sleeps). If I then try to re-awake it, that doesn't work, and I have to press the power button until the laptop reboots.
What is going on? What should I change/check to have this setup working as I want it to?