Once you get into your bios, you'll have to just look at everything, every tab. You'll come across a tab for the USB. Sorry but bios is different with each motherboard, so specifics are hard. On my Asus board it's under advanced - USB configuration. What it does is allow for USB to wake/turn on the pc. You'll be looking for the switch where your mouse is listed as a USB to do that. Set it to disable or remove the mouse from that listing. In order to turn on the pc, the port has to remain active/on so the mouse stays on.