Ditto AKcrab. Test this with any external monitor. If it is what I think it is, try taking the brightness all the way down, then back up, and repeat. If you're having this sort of issue, changing the brightness usually sets it off.
If it's not the inverter board or the reed, it'll be the logic board itself which will be replaced. Regardless of whether it's still under warranty or not, you should have some sort of service warranty on the logic board. How long ago was it replaced?