Television and Home Theater

I own a Hitachi 51F500 rear projection TV.  The other day I heard some loud noises (sounded like when you tap a microphone that's turned up).  I heard this noise a few times and the TV would shut itself off and on.  One time I noticed that before the TV shut itself off . . . the word "stop" appeared on screen.

The TV would not allow me to shut it off so I unplugged it for the evening.  The same problem is still happening. 

Could anyone please help me with my problem with my tv. Went to turn the tv on and had no picture just a black screen with good clear crisp sound.

Hello Everyone, I have a JVC AC-27720 TV and recently I started to have issues where I would get a horizontal line across the display.  After a while, or a few good whacks to the side of the TV, the picture would come back for a long time or maybe 15 minutes later.