Not that I know anything about HP Pavilions, but I'll have a go!
Can you tell us what version of HP Pavilion and what version of Windows you have. There are many models of the Pavilion, and the model number will probably help someone come up with the right answer. At what stage of the boot sequence do you get the warning? If it's before Windows starts up, then it has to be a BIOS setting. If the message is after Windows starts, do you have a hardware monitoring utility installed?