Can someone tell me why the picture on my television has begun flashing on and off? It started about a month ago only flashing when I would turn it on. After a few minutes it would stop, but has progressively gotten worse to the point that it is flasing almost continuously. Thank you.

Sounds like something to do with the hi voltage circuit going into the back of the screen. Definitely a service job. Depends on the age of the TV, may be worth buying new.

Depending on the age of the TV, it might be the tube that's gone bad. I'd just get a new set.