Receivers and Audio Components

i have a Sharp stereo and for the past few months everytime i go to turn it on it says "protect" and won't let me do anything. anyone know what to do? thank you!

My components are:

Receiver: RCA RT2500 Home Theatre 5.1 Dolby DTS

DVD: RCA RC5240P

TV: Sharp 36U-F510

I'm
using red, white and yellow plugs.  I have no idea if they're
called analog or coaxial (and have no idea which to choose when setting
the receiver - I've tried both).  The plugs came with the whole
unit and I may have purchased additional at Radio Shack, so I guess
these are just normal plugs.

Problem: 

I have an Aiwa system which has suddenly become unable to receive FM stations. It works perfectly on LW and MW but all I get on FM is very loud static. I have checked everything that I can think of and although it is not in a position where I can plug in an external aerial, I have tried it in another room where I can,but with the same result. In addition, other audios work perfectly in the offending HI FI's normal position. When I first switch on there is almost normal sound for a few seconds and then static! Any ideas, please??