Quote Originally Posted by fchody View Post
... I deleted the whole directory of the device. Everything was removed. I checked it again in explorer before disconnect the DS from the PC. Than i disconnected the device from the computer, started up the device. The device started up normaly. Than i reconnceted the device to computer. Once connected i openened explorer. What did a i see? Every map and every single file was back on place. Unbelievable but true...
Not unbelievable, on the contrary.
These are the main symptoms of a faulty chip (it does not have to be completely defective).

If in doubt, there is another option:
Boot your PC from usb drive. Use some Live Linux or some of the boot images with older Windows versions (7/8), like SergejStrelec. Then try to remove something from device.