The HD500 has a known issue with poor USB connectors, Many of us have had them break (the central tab) and then fail to connect. Trying to contact any of the list of authorized repair centers is just foolishness as they don't answer their emails. Line 6 ignores that this is their issue. I have had to take mine to a techie locally and had him install a new USB connector on the board. The only problem now is, evidently when the middle section came out, the pins touched and the board no longer talks to the USB, so I am still screwed. If yours hasn't broken yet, I would use EXTREME care in plugging and unplugging your USB cable.
