What would cause a 2 yr old kitchen faucet to begin squealing and pulsating?

It's a dual handled faucet that's worked great until last week when I noticed it squealing a bit. Now it squeals a high pitch sound constantly, and even started to pulsate like an adjustable shower head this morning. It does it with just the hot turned on, or just the cold on, and with both handles on at the same time.