Pulsating Water Pipes When Filling Toilet?

I have a Toto Drake 1.6 gallon, ADA hight, almost 2 years old. The supply pipes have suddenly started pulsating when I fush. The pulsating is so strong (actually scary) that some pipes in the basement (2 flights down) shake. The pulsating lasts until the tank is full. This does not happen to other fixtures in the house.

Any ideas what might cause this?

(I suspect it might be the fill valve. But I have never seen one fail in only 2 years. If it is the valve, could it be repaired, or must I replace it?)

Thanks.

First, make sure that the shutoff is fully opened. If that doesn't solve it, if it's a multi-turn valve verses a 1/4-turn one, I'd suggest just replacing it. It's possible the fill valve has some crud caught in it. Depending on which one is in your toilet, if it is the one made for them by Korky, you can replace the seal for about $3 (buy it at Lowes or a plumbing supply house). Takes about a minute, instructions on the card. If your fill valve has a screw on the top, if it is the bad part, you need to replace the whole valve. I'd vote for the shutoff, though.