What is this horrible sound my computer is making?

[enhancedstudios]

Every now and then my computer just starts making this horrible nonstop ambulance sounding noise coming from the PC speaker... I've done full system scans several times to check for viruses... Norton Pro 2003, fully updated... and nothing is returned... and nothing i can do stops the noise unless i turn my computer off.

what could this possibly be? it's driving me insane. help!

[sKuLLsHoT]

sounds like the thermal protection alarm some mobo's have

i would go into the bios and check the temperature readouts, you can bet (maybe falsely) something is showing to be at fault

[tukinnam]

or the mobo protection might be a software if u installed any..