Digital audio sync problem

This is not necessarily a problem with my HTS3544, but this issue somewhat limits the use for digital audio inputs - the video signal is not synced with the digital audio. My Philips home theater has a sync setting, but I am not sure if it is only meant to be active while playing DVDs. I think that the TV should have some syncing mechanism. What's worse, it appears that the amount of correction needed changes from time to time. In my experience, the video and audio became so out of sync that I had to eventually resort to using my TV's speakers.