The disk cannot be locked because the disk drive is still mounted. That means, the disk drive is still in use for some reason. Create an FDISK, and boot from the floppy. Go into your BIOS and make the Hardisk boot LAST in boot order, and the floppy boot FIRST. Then put in the FDISK you created, and use that to format the C drive. The FDISK has specific menu based DOS commands, so it won't be hard either. Just go to help section on Microsofts site, and type in FDISK, and it will tell you how to create one on your OS. GL!