I had the same problem today. My HD500 was in tuner mode... i tried everything above (e.g. tried different USB ports on computer, 2nd cable, etc.) and nothing worked. On a whim I changed the setting from "tuner" to my preset 1A (not sure if it matters which preset), tried again and it worked just fine. So it may be that the HD500 needs to be in a certain mode. Hope this helps! Good Luck!