When you run the convert driveltr: /FS:NTFS command, at the next boot, the FAT partition specified will be converted to NTFS. NT is signalled to perform the conversion by checking the BootExecute key at boot time. The key's normal contents, autocheck autochk * is replaced by autoconv \DosDevices\driveltr: /FS:NTFS. To stop, the conversion, set the key back to its normal string value prior to rebooting. The full key follows