If you are trying to format drive J from within Windows, you might have better luck if you delete that partition using FDISK when Windows is not running. This involves booting into DOS from a Windows 95 or Windows 98 startup floppy disk (you can create one by downloading the creation file from http://www.bootdisk.com)
. Boot from it, start FDISK which is on the floppy, select the appropriate drive, choose the option to delete "Non-DOS partition" if it is an NTFS one. Now create a new partition with FDISK. Remove floppy. Restart Windows, format the new partition using the Windows computer management tools.