M3800 only wakes up from suspend if USB device is inserted in USB port, otherwise reboots.

My laptop (M3800) always goes to sleep ok ("suspend to ram" S3 mode).

But it only wakes up correctly if the sleep+resume is performed while a USB port is used (key, mouse, etc plugged in). If not, it simply performs a normal start, hence losing the session.

BIOS version: A09. I had to enable "USB wake support" in order to allow the computer to turn on when being opened. Otherwise it would just stay off and require a hard restart (pressing the power button for 10 secs).

I've been digging about this for a while and could not find answers. Any help will be appreciated!

PS: don't ask me to update the video drivers. It's a hardware+BIOS problem here.