Sony Model: STR-DG800

You've got a short in one of your speaker wires either at the receiver (most common) or at the speaker itself. you should only have a 1/2" of each side of the speaker wire stripped to put on each terminal, and when you strip them, twist them so there are no frays in the strands that will touch the other terminal. The receiver is protecting itself from harm. Turn it off then disconnect all speaker wires, examine each wire carefully before reinstalling, then turn the receiver back on. If it still says protection, look at each speaker and reconnect your wires the same way. If you still have a problem, disconnect the wires again at the receiver and turn on, at this point, if it say's protection, it needs to be serviced. Hope this helps