Just wanted to add another data point to this thread. I bought a refurbished 5D2 and it arrived last week. Using it with a new Transcend 400x 32GB card and getting the Err 02 when trying to import videos from the camera.
Right now I have the card plugged into my computer with a card reader and doing a read/write test for bad blocks on the card. It won't finish for a couple more hours but after checking 40% of the card, no problems have been found yet.
Not sure what I should do at this point. If the card works fine with my computer, does that point to the issue being with the camera? I could order a new card of a different brand and see if that works, but I've had good luck with Transcends in the past and other brands can cost a lot more. Either way, I have to figure something out before the 14 day return policy runs out on me.