"Protect" error - HTZ110

Question

When I switch on my HTZ110 Samsung Home Theatre System the digital screen on the dvd player appears with the word “PROTECT” and the dvd player immediately switches off? Then I held the power-on button the second time around then the dvd player managed to switch on, I then put in a music CD, I could see the CD playing
but WITHOUT sound. What is the problem and how do I solve this.

same problem here with samsung HT-Z110