Right on, Copernicum, excellent advice ... my MFT started giving me "indexing device" notifications a few weeks ago, even though the USB drive containing my music hadn't been moved form it's slot for over a month.
I thought it strange and went through the hassle of a master reset (hassle because of having to re-pair phones but great because it exists as a trouble shooting option) and voila, voice commands back on line and good to go!
Gold Nugget: '12, Spec 400A, Winter Pckg, Yellow Blaze HB
Mods: Llumar Tint:35 frnt, 20 rear; K&N drop-in; Splashguards
Hatch Nation #174