Black & white picture on Samsung HD tv?

There have been a few problems lately with my tv, first of all when we turned the on button on it keeps clicking on and off and takes a few minutes to actually come on. Now we have problems with the colour, sometimes its totally black and white and others its like a negative print or just really dark. Also, lately it won't play HD, we have a Sky HD box but if the HDMI cable is plugged in its just black & white or no HD at all and its gone back to the normal old style sky tv guide, not HD.

Today, I now have the added extra on top of all those problems of not receiving a satelite signal at all, so can't watch sky on it. I don't know if its the tv as I initially thought because of the clicking on and off or the sky too now!!

Can anyone help?