When I turn on the TV the picture comes on then after a few seconds the screen goes black, what does this mean and how do I fix it? I still get sound and when the picture is on (for those few seconds) it is still good quality.

What device do you use for playing the video? PC / DVD player?

Shut everything down and take all cables out of the TV.
Switch the TV on and try to access the normal TV Menu. If you are able to do this then the chances are the cables are wrong or the TV settings have to be changed.

Try other playback devices, if they do the same then the chances are that your TV is faulty.


Hope this helps
Grant

Model number of the TV? And as Grant asked, are you able to pull up the TV menu?