Help - faucet noise/shutdown

[Roastonbone]

Hi all. We've got two sinks in our master bathroom and I recently noticed a strange problem. Both faucets work fine individually. Both faucets work fine while the shower is running. But if I turn on one faucet, then the other, as soon as I get past a certain level I hear a nasty grindy/groany noise and the water shuts off at both faucets. If I turn off both, everything is back to normal. Anyone have any idea what's going on here?

[Spork]

Could it be water hammer?

[Greg]

Sounds like a loose washer on one or more valves.  Might have to do with them both being on one angle stop under the sink if they are on the same angle stop.

[Roastonbone]

Thanks for the input.
They are on the same angle stop; I'll poke around.

[Greg]

I suspect the sealing washer for the angle stop has a loose screw, or is somehow floating in the valve.  You may be able to replace the washer of the angle stop, but for not much more trouble or $ you can replace the angle stop.  They do have a finite life span.