I recently updated the firmware on my HD 500 when I restarted my HD 500 my buttons no longer responded. after re installing latest firmware it continued to do the same thing. after numerous attempts to change USB cables and computers I determined it was not a software or connection. I became curious about the voltage needed to power the very ex guitar through the VDI cable and realized it is possibly a strain on the overall voltage supplied to the HD 500. this in my opinion is clearly a manufacturing defect that has been rearing its head for quite some time now. it would be prudent of line 6 and or Yamaha to resolve this issue by supplying better power supplies for users that are using the HD 500 VDI cable to power their Variax guitars