[baronrus]

Another thought after you add some epubs say 100 or so do you unplug your kobo and let it process the content? or do you just keep adding them until it crashes? how are you adding them? Through calibre I assume? If so have you tried adding the files directly to the card via the save to disk option in calibre and then letting the device process them?

I use sd card as the primary storage space for my kobo and although I had some initial hicups getting the card formatted correctly once I did that I have had very little trouble at all.

I would be mostly suspicious of it being a 'buggy' file as opposed to a 'buggy' card slot.