might not be enough solvent to dissolve it all, or it migh be too cold, or some solvent has evaporated (thus no longer having enough)... many reasons can lead to crashed stuff.
You can always put it in a warm water bath to help slowly raise the temps and try to see if it will redissolve. Otherwise, there's really no harm in taking it that way since your body will still absorb it. Provided that it's not a contaminant of course...