Problem with HDMI, screen goes black, then restarts

My older plasma TV has 1 HDMI and two componenet IN ports. The DVD player and the WDTV player were both set to use the component interfaces and the TV was using the HDMI. Something went wrong with the TV and the component picture went from good to a sort of reverse negative image in certain highlights, the pixels are all silvery near the edges of images. This loss of quality occurred on both the DVD and the WDTV pictures so I surmised that the TV had developed an issue with it’s componenet interface. I hooked the WDTV to the HDMI and everything is back to better than normal and I have ordered an HDMI switch however I have noticed a problem with this connection. When playing back movies on the WDTV the picture will go totally black, the TV then shows the HDMI symbol in the upper left, the TV then shows the resolution scan rate in the lower right then the movie playing on the WDTV comes back, this takes a second or two and then it does the same thing a few minutes later. On some movies it is quite bad, occurring constantly. It never does this when the TV is hooked up to the HDMI and the TV switches between HD and regulart channels often, the resolution scan rate comes up in the lower right but the picture is never lost and the HDMI symbol never appears in the upper left, only the WDTV does this. I have tried setting the WDTV to auto, I have selected the resolution, nothing works, it always does this when the WDTV ius connected over HDMI. When I set the WDTV to 1080i/50hz the WDTV says the TV doesn’t support that resolution, that is the resolution that the computer selects for the connected TV when it acts as the monitor for the computer. I have tried all the settings and they all do the same thing. Any ideas on what could be causing this? My WDTV says it has the latest firmware and it is connected by cable to the home network and everything else works fine.

The HDMI port might be dirty, you can also try using another HDMI cable.