Although renaming the folder on the computer, of course, shouldn't cause the loss of its contents I suppose this could happen if the camera and computer have different ideas of the implementation of the FAT filesystem. This, in turn, could be as FAT is a "de-facto", not a "proper", formal standard.
For this reason (*) I'm in the habit of formatting the card in the camera every time I've copied its contents to the computer. This way, the camera always gets to work with a mint file system that matches its idea of a proper implementation. This, of course, takes care of implemention differences only until the card is put in the computer, at which point one should avoid any operations that result in writing on the card (such as a folder rename) at least until all the pictures are safely on the hard disk. As a safety measure in this respect one could have the card write-protect switch in the read-only position while the card is in the computer.
(*) Also, this way I don't have to keep track of whether particular images have been copied already, which is practically impossible with large cards / in the long run anyway.
Last edited by jolepp; 10-16-2010 at 05:51 AM.
Reason: typo fix