why is my pc making a weird grunting noise !

[DartKarizma]

Hi , I Notice Recently My Pc Has Been Making A Really Weird Grunting Noise , I Have Looked All Over The Internet And I Have Found Nothing That Sounds Like Mine . I Need Help . Whenever It's Makes The Weird Grunting Noise A Red Light Flashes On The Case Of My PC

 

[popatim]

Might the Red light be the Disk activity indicator?
Does it flash like a madhouse when you are restarting or booting the pc up?
Also, check your optical drives, perhaps someone left a disk inside.