I had a very similar problem with my 64s. After many days of head scratching and frustration, I discovered that it was the USB cables I was using that caused my connection issues. Get a good quality USB cable (not expensive, but good quality). I was using an "audiophile" USB cable which was very well constructed. Turns out that the 64s did not like that cable. When I went to a regular USB cable (Tripp Lite), it worked great. Try that. I hope this helps. Oh and try to keep the length of the cable 10 feet or shorter.