Just to chime in on this topic:

My player, during playback in my car at speed, will try to access the hard drive. There is audible clicking of the drives, the "W" icon will come up and the player either freezes for a few seconds or the player fatally locks up. After a fatal lock up there are no hard drives detected on boot.

Possibly a vibration issue?

FYI, I have contacted DavidM