Originally received invalid B-tree node size message, disk utility could not fix. I could see both master and slave HD. Bought Data Rescue 2 (instead of Disk Warrior) and suddenly can't see HD, in Data Rescue or Disk Utility. I was thinking about reformating slave HD with operating system, and then trying to retrieve HD data that way. Is this possible? If I can't see HD, what can I do? The HD is less than a year old, so I can send it back to the company, West. Dig., but loose precious data. Any suggestions.