Are you getting the green ring around the yolk still?
Then I have the easiest boiled egg technique for you. There is no timing or thinking involved here, and the eggs come out perfect every time!
Situate the eggs in a pan and cover with cold water (add a splash of white vinegar for easy peeling later). Place the pan on the burner and turn the heat to medium. Bring the water to a low boil. Big bubbles should be rising but not moving rapidly. No need to bring to a rolling, fast boil. Once the water is boiling, turn off the burner and remove the pan from the heat. Allow the eggs to rest in the hot water for a couple of minutes. Bring the pan to the sink. Without pouring out the hot water, add cold water. Let the cold water overflow the pan and bring the water temperature down. When the water is cool enough that you can submerge your hand, remove the eggs from the pan. Done! Crack an egg, slice it in half and reveal a beautiful perfectly cooked, pure yellow yolk.
What did I say?? Perfect!
*update 2.28.13: Feedback has suggested that I have more luck with the shells than most. While the yolks are perfect yellow the peels are proving to be difficult for some. I wish I had better answers. Use a good glug of white vinegar in the boil water to aid in peeling. Use this recipe when perfect whites are not important but yellow yolks are.