Mitsubishi WD-65733 Synch'ing problems

We purchased a Mitsubishi WD-65733 in 2008, it is still under warranty. Initially it worked fine, when turned on it would display the source it was connected to. A few weeks after we purchased it, we noticed that when we turned it on it would not display the source it was attached to (e.g. DVR attached with S-Video cabling), and that we had to re-select the source for it to display. That was annoying but we lived with it. Once we attached an HD source (Playstation 3) with an HDMI cable, we noticed that every so often the picture would disappear and the TV would re-synch (to 1080p) and come back on. We recently purchased a Philips BluRay Player (DBP7200) and the synch issue has become muchworse - every so often the picture disappears for a number of seconds, then the TV re-synchs to 1080p and continues.

Because the TV has the synch issue when we turn it on, and the 1080p synch issue occurs with two different HD sources, we think it is the TV that is the problem. Please let me know if this is true, or any ways to fix it, or what we should do next.

thanks, PAM

I will check another hdmi cable, I had thought about that, but what about having to always re-select the source when the TV is turned on? That occurs when not using the hdmi inputs...