pfSense

this is a hardware-specific issue of some sort, not an issue in our code. Judging by Ermal's analysis, ACPI seems likely. Many issues along these lines are BIOS bugs, so upgrading to the latest BIOS if not already is a good first step. Certain BIOS settings may resolve, such as resetting it to defaults in case something is unusually configured in it. If all that fails, replicate on stock FreeBSD and report upstream.

Start a thread on the forum to continue discussion with a much wider audience and we can help try to narrow down what's happening and find a resolution.