try this
Load troublesome card into a usb cardreader, plug into computer, it will appear as a disk drive in "my computer" window, right click on it, from the context sensitive menu select format, or full format if it appears, format the disk.
Put it back in camera, if all is well you should get no error messages and will be able to write files to it.
If this does not work it simply means the card is faulty.
if it is within the warrenty period, take it back to the dealer, they will of course go though the same procedure
outline above, this should resolve the issue.
nrb, January 2009
