Sandisk is nearly always a winner.
I think the library is stored internally, but I wouldn't be surprised if clearing a few tracks off the stick helped it along. Clear some space, turn off Autoplay, swap sticks with ignition off, and let it rebuild the index before starting the engine. Rebuilding shouldn't take that long, and if your Sandisk has LEDs on it, you can easily see when it's finished.
Let us know!