I use a Sherwood DVD player to play CDs and DVDs. Yesterday, I discovered that while CDs play fine, DVDs don't play as loud, freeze intermittently and sound rough. It is consistent on DVDs. Do DVD players have different lasers - one for CDs and another for DVDs? Is there something else going on? I even tried playing DVDs in PCM stereo instead of DTS/DD and I still have the problem.