Screeching noise

I've been having a screeching noise in my 98 Lumina, the noise sounds like the power steering, but the steering is fine. The noise is intermittent but does last for long periods of time while driving. The strange thing is that when I apply the brakes the screeching stops altogether, but when I release the brakes it starts again. I think I can smell burning also, does anyone have any ideas?

Thanks

This is usaully the front pad wear indicators contacting the rotors, have ft brakes checked, soon!

Thanks for the diagnosis. I'll get them checked asap. Cheers!