HP Pavilion laptop Media Center Problems

My laptop is only 7 months old (Sorry, I’m not a Geek.) The Media Center used to play DVDs well but suddenly now a message appears, “Decoder error, please restart…” My kids surf websites all the time and I do have anti-virus, firewalls and spam controls? I tried to re-install the Media Player using the instructions from my original kit, but to no avail.