Corrupted card or is it the camera?

My cousin shoots professionally. He has been using his 1DIV, and loves it. In the past month, he picked up a 5DIII. He loves that even better. I've seen images from it, and they're outstanding.

He called me to say that one of his 64Gb SanDisk cards became corrupted. They are the Extreme Pro 90Mb/s. He's had these cards when they first came out (I blanched when he told me he spent $550 each, but I guess it pays for itself when you make money with it).

He shot RAW + jpg. Fortunately, he recovered the jpgs, but the RAWs were unrecoverable. The card, once removed from the camera, could not be read once it was put back into the camera (he always shuts the camera off before removing the card.

He called me a couple of days later, and his 64 Gb Lexar also became corrupted. He ran a back up card, which was fine.

Now he's all worried, and is wondering if it's the card or the camera. Cards do become corrupted, but they went belly up so close together. It's weird. Luckily, there is a lifetime warranty on them, so he'll get them replaced.

He's got one more of the 64 SanDisks, so he's going to see what happens on his next shoot.

Any other 5DIII owners have this happen to you?

Does he mix the cards between cameras? They recommend you format if you change devices, though it *should* work. I mean, I never had to format floppies going from one computer to another, or USB keys, or portable hard drives.

I have a dead 8GB Sandisk Extreme SD. It never left the camera, as we always transfer pics via USB...it just decided to die one day, so yeah, it can happen. It's been a year and I haven't gotten around to claiming a replacement via warranty.

I checked with him, and the card is no longer detectable in another camera, or the PC. The other thing I told him to try, was to reformat the card, if possible, in the PC, rather the camera. He said that didn't work, either. So, it sounds like it's dead. From what he told me, he formats the cards in the camera, though he didn't format it when he moved it from the IDIV.

That thing about moving from one device to another....hmmm. That's definitely worth checking into.

I just have a hard time believing it's the camera. For two to go, though, is an oddity, but not impossible. He's put 100s of thousands of images on both those cards, so there has been a lot of write/re-writes to them.