Haven't seen a post on card compatiblity issues, so I thought I'd pass this on. I purchased a Kingston 32GB ultimate 600X CF card to use with my D4. To my surprise when I put it in the camera, it gave me an error message. Pulling out the manual (which I should have done first), they only list Lexar and SanDisk CF cards as compatible.
I bought the Kingston because they were highly rated memory cards. I guess if they're not compatible, it doesn't matter what the rating is.
Haven't had this issue with other type cards, but I'll be sticking to the Lexar CF cards from now on. Hopefully, their XQD cards will be compatible with the D4.