Turned on my tv one afternoon last week, and the satellite receiver came on, as well as the tv.......sound, but no picture.......just a black screen. Thought it was just the channel having problems, but I changed channels, and still no picture, I couldn't bring up the tv menu either, so I knew it was with the tv.Turned the tv off, waited for the fan to go off, and turned it back on, and got a picture. Hasn't happened again since. Is that an indication of the bulb or ballast on it's way out, or could it be something else? Om that note, what is the average life of the ballast, and what are signs of it going, if this isn't one of them?Thanks in advance!