You mean to tell me that (1) the machine is powered down, and (2) the hard disk activity light blinks on its own - while all the other indicator lights are out? We're in X-File territory now... ...

If the speakers are disconnected, and there's no disks in his floppy/cd-rom drives, then the only thing that can click when powering down would be the hard drive, in which case, it can't be cured by...