Hope i'm not too late for this post but here's what happened to me
..Purchased an 8gig SDHC card for the K10D..
Camera wouldnt read it "memory card error" message.
Tried it in the istDs and worked perfect????...
Forgot about it and just run with what other cards i had , then the other day at the local hardly Normans shop they had the 8 gig Lexma>> SDHC cards on special so i bought one and works perfect in the K10D???.
Maybe it the particular brand the camera doesnt like that you are using??..
Did you purchas eit off fleabay???
Cheers