Hmmm, I see I made a lot of posts on this thread. Since then, I have been working on other projects and not using SD cards on my T3.6 boards, so I've had no follow-up.

Frank, what size SD card are you using? Have you tried using several different cards, and especially maybe with smaller memory than this card? From what Bill Greiman has said in the past, not all cards are created equal, and some may be pirated knock-offs, even if they're labelled as from an official manufacturer. You should look at the info on the card using whatever means you can, and see if it looks at all suspicious.