Noises problem
2005 BMW Z4 6 cyl Two Wheel Drive Automatic 83000 miles

When starting up the engine, I suddenly had this strange whining (practically a sharp drilling sound) coming from engine, and this would fade in and out, especially at low revs. Took it into garage and have now been told it wouldnt start, so need to change starter. Am not convinvced however that the starter would have been the original cause of this noise. Any ideas would be welcome!

thanks