Believe me, I've tried every combination of every factor
SD card in, SD card out, I've even tested things like light, heat (I did not put the device in oven). The nature of the problems remains unknown, and its occurrence has been random.
Irex just sent me pre-paid ups box to send them the device, and they said they'll be examining the device first. This is good for a start. I would be very happy to get a replacement, but in my case, even a repair is good enough.
Funny thing is, looking at other people's experience with the device, I still think I've been unlucky about my particular unit. For the next 6-8 months, for a guy living in London, with my requirements, DR1000S is still the only option. When it works, I love the device, and it does all I want, and saves me from lots of back pain, saves lots of trees. It is just that I can't effort another one if this process becomes a dead end. I've turned into the joke of my department at UCL, from being the cool guy with the fancy e-reader
All the best
Seref