System is Arch Linux. NTFS-3G is installed. I have had this problem on Gnome (Nautilus) and KDE (Dolphin). I already tried fixing it with Testdisk. No success. Any help is appreciated.
UPDATE: I have re-formatted the disk and it is working now. Thank you for all your suggestions and tips.
I ran Nautilus with root privileges, same error message. I will read about FUSE support, though, thanks.