Hi. With regard to the most recent remark, I believe there is indeed a difference between formatting with a computer and doing the same with the camera's firmware. In this case, I am referring to the NIKON dslr cameras.
With the latter, when you do a format, all images will be erased, except for the blank folder to which captures are saved, plus there is a system file called Nikon001.dsc i believe it contains the machine codes used by the camera to recognize and manage the saved images in the folder. However, if you format the card using the computer, everything on the card is erased, everything! There will not be any blank folder or system file. I suspect this may be a reason why some memory cards were not able to function well in the camera. Pls do correct me if I am wrong.