Waves on screen

I've got waves when scrolling on the screen, its just started doing it from what i can see for no reason, does anyone know why?

 

is it a CRT or LCD monitor? It could also be EMI causing it .

 

Its an LCD monitor, i tried to change it but it made no difference, tried the mouse & keyboard aswell and no difference, whats EMI?

 

http://en.wikipedia.org/wiki/Electromagnetic_interference

Something like a device or something running in your living room interfering with the monitor. Your monitor cable could be bad or the monitor may be going out. The pc video card could be going out as well.

 

No its not EMI it doesn't look like that, the only time it does it is when i scroll down its like a big wave or ripple going down the screen and it takes for ages to get down

 

Can anyone else help me? a bit more info i've found out its something to do with the graphics