I had almost this exact situation happen to me last week. I also found one other victim. We were all using Gigabyte EP45 mobos connected to a mac in Target Disk Mode (where the mac acts as an external firewire drive).

Obviously this is something to avoid in the future, but is it Mac's fault in the way they do target disk mode, or is it Gigabyte's fault in their Firewire hardware, or is it user error (something we did that screwed it up)?

Any insight would be helpful.