On a system that has at least two OSes, Windows NT in a NTFS partition, and Windows 2000 or XP (FAT or NTFS), when running Windows 2000/XP, all NTFS partitions on the system are converted from NTFS 1.0 to the newer NTFS 3.0 or 3.1 file system.
Windows NT 4.0 SP3 or older
If you are using NT 4.0 SP3 or older, Windows NT will no longer boot. This occurs since Windows NT SP3 and older does not understand the NTFS 3.0 file system. The NT partition's data can still be accessed from Windows 2000. There is no way to undo or change the NTFS file system back to NTFS 1.0 once modified by Windows 2000. By default System Commander 7 (but not older versions) will use super-hiding to help prevent a newer 2000/XP from changing the NTFS file system.
Windows NT 4.0 SP4 or higher
In this case, Windows NT has some understanding of NTFS 3.0 (converted from Windows 2000), and should boot and run normally. The tools in Windows NT (all service packs) for disk maintenance and diagnostics, such as CHECKDSK do not understand NTFS 3.0 and will refuse to run. You can boot into Windows 2000 and run its newer disk utilities on the NT partition.
If you run Windows XP, all NT versions do not understand the new NTFS 3.1 format and will no longer run. There is no way to revese this process once done. By default System Commander 7 (but not older versions) will use super-hiding to help prevent a newer 2000/XP from changing the NTFS file system.
If you wish to have both Windows NT and Windows 2000/XP on the same system, we recommend using only a FAT partition for Windows NT. V Communications' current tools, such as DriveWorks or Partition Commander include a converter to make a NTFS partition into a FAT partition. If this is done BEFORE Windows 2000/XP is installed, the Windows NT should work fine with Windows 2000 or XP in another partition. It is also be possible to have Windows 2000/XP in NTFS if the service pack 5/6 for Windows NT are installed before installing Windows 2000/XP.