Problems with the stereo 2002 GP GT

Hey everyone,

i have a 2002 GP GT with the Monsoon HU and bose speakers with the amp in the back

well now it has been acting up and is to the point it doesnt work at all

it first started that after listening for a little bit you would get a loud screeching noise (like gettin feedback from a mic) and i would turn it off and all would be normal until it decides to do it again

i have been leaving it off for a while because whats the point when it will just screech and i decided to turn it on and no sound whatsoever.
when the HU is on radio there is no sound, when you put a cd in it goes it and appears to be reading the cd but no sound

any ideas of what this problem might be???

thanks in advanced

Mike