I recently purchased a Sony DAV-SR4W and I'm very impressed with it. However when I watch DVDs, the sound and video are sometimes a bit out of sync, and sometimes even close to a second out. I've tried a few different DVDs, all brand new, and they seem to have the same problem. Any ideas as to what could be causing this? do I have a faulty system? It seems a little strange as its only with DVDs. I have my LCD TV audio outputting through the speakers and it perfectly in sync.