New(ish) Samsung 64GB card acting up on 6D and PC.

[Chele]

I have 6D with ML (Nightly.2016May16.6D116) installed.  Suddenly camera says to format card or reinsert it, PC says to format it.  The card is fairly new, I expect it to be original, and had been working fine until this time.  I always format the card in the camera after transferring the pictures to the PC, I doubt this card has been formatted more than 80x.  Also, I always wait for the door-light on the camera to stop flashing before removing the card from the camera.  I have pictures on the card but don't really care about the card or the pictures, so that is not the issue.  I have not formatted the card yet in hopes of finding out what could have caused this and how to avoid it in the future. 

BTW,
Don't know if this is related:
Several times(no pattern to it) the DualISO feature was not available on this firmware version, rebooting the camera brought the feature back.  I use very few features on ML, but the ones I use, I use very often!  DualIso is one of those feature.
Now that the card is acting up, the door-light doesn't come on when the door is opened.

[Walter Schulz]

Cards acting weird or dying may happen. Been there, done that.
Contact Samsung support and ask for replacement.

Dual-ISO not available will happen after improper shutdown. Default ML setting will cause modules not loading after such an incident.

[Chele]

Thanks Walter,

Like I said, I'm not concerned about the card itself -- I know cards will eventually fail, I was hoping to learn what to avoid/improve:)  I know the improper shutdown of the camera is a whining point for some, I have always been very careful about doing it properly.

[a1ex]

Next time when some module is not loading, check the module tab - if it's missing, you had a bad shutdown.

Of course, the reason for a bad shutdown can be either user error or ML bug, so you should try to narrow it down - if you suspect a ML bug, try to find out how to reproduce it.