Nokia has stated that the memory card slots in N800 have slightly different voltage regulation so it's possible that, depending on the memory card, the slots could behave slightly differently. I suppose the best interim result would be to ascertain which make to put in each slot.

My own opinion is that this is a ridiculous situation which has been going on for far too long. As with all things N800, Nokia needs to devote more resources to it. But then maybe this, too, is a deliberate decision. It all makes perfect sense when explained, don’t you know?