MiniSD actually. I had the miniSD card that game with the n800 in the Internal bay (with full sized SD adapter). Just right now i tried rebooting it and the miniSD didn't show up in the file manager. I tried other cards in that bay and it works fine. The card still works on my computer so I tried taking the miniSD card and formatting it with my computer but that still didn't work. I've read a few posts about people having problems with SD cards and the n800, but i can't figure out what's wrong. Anyone have any ideas as to what might have happened?

Happend to me also. 2 miniSD kingstone wasted.
I have now one AData SD and one Crucial SD, bot no problems.

Ofcourse i blaim the kingstone miniSD

I believe Kingston offers a lifetime warranty on their cards. You may want to return them for replacement.

my sdcard keeps going into Read Only mode. it is an adata 8gig card. i run ubuntu in my laptop, and it shows as read-only too. i dont know if the n800 contributes to this or not. i normally have to format it to get it back

It's being corrupted. You've removing it too early after a file transfer or somesuch.