I have had intermittent problems with the Kobo, mostly just crashing. I had an idea - remove the 2gb SD card. Well, no problems with the Kobo after removal. I left it out for a week, and just re-inserted it, and the Kobo began right away to misbehave.
This leaves me wondering
if the SD card is defective, or if crashing with an SD card is expected behaviour. Anyways, I'm leaving it out for good. I have plenty of space on the main drive.