Dell Latitude D620 making a beeping noise

Hi can anyone please help me

I have got a Dell Latitude D620 that has recently started making a beeping noise every 3 seconds. I dont know where it is comming from or what to do.
My laptop doesnt freeze or restart its just the constant annoying beeping noise and if i mute the sound on the laptop it goes away with the rest of all sounds.
Specs of laptop: Processor - T5600 @ 1.83 GHz 1.83 GHz
Ram - 2.00 GB
System - 32 bit- Operating System (Vista)
Laptop - Dell Latitude D620

Any info will be greatly appreciated.
Thanks

 

Have you checked in your sounds / notifications in Control Panel to see if anything looks out of the ordinary? Choose no sounds and then see if it goes away.