I have no idea for sure, but here's a few wild guesses of things that could cause similar issues...
First (ok before first, though I'm writing this last - don't ask, I guess i'm conversationally dyslexic or something
), I'm assuming that you can turn the PC on and off normally, is that correct? If not then let me know and I'll put out new ideas.
First what is an AVR? My first thought was the switch on the back of PSUs but then I thought maybe a piece of Audio/visual equipment, then just figured I must be stupid so I'll ask
Anyways, on to some WAGs:
Wake on Lan or wake on USB something or other setting in BIOS for a device like a recorder
Last power state setting in BIOS for an external (to the motherboard) power switch.