Comp's making funky noise

my comps a tower and i usually leave it in stand by mode but shut it down every once in a while too but just a few days ago i was gonna be gone for the whole day so i shut it down and when i turned it on the next day right after it loaded the XP screen it started making this funky and flippin annoying noise.

it repeats and it never stops unless i turn it off, its like a click beeep kuhclick real fast like 1 1/2 seconds. i didnt know what to do cause when i cover the fan vents in the back it sounds the same and for the heck of it i ran computer scan with McAfee. please help, what the heck could be making this noise!

 

Could it be a heat alarm? Take of the side of the computer, clean out the dust and be sure the heat sink or fan on top of the CPU is free of dust. Before you close it up, turn on the computer. If it still makes the same strange sound, hold an empty paper towel roll to your ear and see if you can figure out what exactly is making the sound.

 

ok so i called my bro and asked him about it since its his old comp and he told me how to take off the side panel and now i can definitely tell that the noise is coming from the hard drive... great! so im running a defrag to see if that does anything but i honestly have no idea why its making this noise or how to get it to stop. gwaarrrg!

 

It means your drive is going bad mechanically. All you can do is backup your stuff right away before it dies.