well.. if you still wanna defrag, either connect it to your card reader inbuilt or buy a usb multi card reader.
and about the image files failing to boot, everytime you make a bootable usb drive, always, always format it specially just before making the drive bootable to the required file format . NTFS or FAT32. but always format. never create a bootable usb drive without first formatting it. quick format is fine.