Computer monitor problem?

I have a computer display is a 17-inch LCD
bought a 1-a-half years of
the past two days have been good but the problem
screen floating up and down the strip itself, only to tell
Rate to 800 * 600 can not see it
who knows how it is going

1.Graphics problem
2.Does not work where other people to take a display to try to do it if you have the card in question if there is no way that your display card does not work out of