Problem with 21" iMac display

Hey all.
I bought a 21" iMac about two years ago, and I have never had ANY problems with it at all. Until about a week ago...

I was using it as normal when all of a sudden, the contrast started to flash brighter intermittently. This continued for a while, then it went completely white and stayed that way for about ten minutes. The picture came back, but it was still flickering. I turned it off for the rest of the day, but it did nothing to help. It is still spazzing out and still goes completely white for periods of time.

Anyone have the same problem, or know what the problem is?
And anyone know how to fix it? Or am I going to have to put it in the shop for some expensive surgery?

here give this a try.

while the computer is off press and hold the "option, command, R, P" keys and keep them down until you hear a second chime, when you hear the second chime let go.

Hey mate, thanks for the tip, but it didn't work, I'm afraid...
In fact, when I held down the keys you suggested, it didn't even make a chime noise

Before taking it on in try to figure out which is at fault; the display or the graphics processor. If you have an external monitor that you can hook up to your iMac, give that a try. The same symptoms occurring on the external monitor would most likely point to a bad graphics processor. If the external display is OK, the problem may be with the video cable to the internal display.

If it turns out to be a bad graphics processor, that would mean a logic board swap as the GPU is soldered to it and can not be changed out separately.

Regards.