Windows 8 has this stupid new feature that tries to index all mass storage devices that you connect to your computer.
The same way OSX does it, it creates a hidden folder on memory cards, USB drives, Hard drives and any mass storage devices, without user intervention and with no easy way to remove it or files inside it using Windows Explorer since the files get flagged with system properties so it won't allow any user to delete them.
To remove that folder, start a command window (WIN+R, cmd, ENTER) as administrator and type the following commands, assuming the drive letter for the card reader or USB storage is "F:", replace that letter with the one assigned to the drive in your system.
(Hit Y when asked to delete)
The location of the "~" symbol depends on the distribution or language of your keyboard, on EN keyboards, it is at the left of the number 1 on top of the Q, use with SHIFT. The ES keyboard doesn't have that symbol and on the LA distribution, it's 2 keys to the right of the P, use with ALT.
Or you can input the symbol using ALT+126.