Potential problem - 1DsMkII & 85 L II

So, I recently purchased a 1DsMarkII and it's been working flawlessly. Today I rented the 85L II and put it on and I had this happen...about 4 shots out of 30 did this

Do you think this is the camera or the lens

It was of OCF as well

HTTP response: 404 | MIME changed to 'text/html' | Byte size: ZERO

looks like a card problem to me.

Thanks for the response

A card problem really? I've had cards go before and never anything like this

this happened with me once when i used a bad card reader. If you used a card reader try using a usb cable.

Another thing to check is whether that particular card has been formatted in your new camera.

Does the problem still happen? Did the new card work? How about other lenses?