Hi I bought a Samsung LN46A550 LCD TV about 6 months ago. I have it connected via an HDMI cable to my HD cable box. I noticed that sometimes when i turn it on i only get the sound but no picture. When I turn it off and on it works fine. I was just concerned that it could result in a bigger problem later on. So i wanted to know if this was a common problem or should I give it to Samsung to get it fixed since it is still under the warranty. BTW this problem happens very rarely. It happened to me around 4 times since i had the tv.
If you bought online I guess Samsung is your only option. Since you didn't mention calling your local retailer, I'd have to guess that to be the case. In any event, don't wait.
Sounds like a "HDMI handshake" issue. You could try and see if there is a firmware update for your HD box, That may solve the problem. Give samsung a call and see what they say otherwise you could send it back to them and have them take a look at the tv.
Do you have other stuff hooked up to your tv by scart as well, dvd player/recorder, surround sound etc.? Sometimes if you have lots of things switched on the tv doesn't know which scart to go with and can show you a blank screen until you choose the correct input on the remote.