Regedit.exe, the Windows 95 registry editor, is included on the Windows NT 4.0 CD-ROM for its' superior search capability. It does not support all the NT data types and does not support Windows NT Registry Security.
If you upgraded to Windows NT from Windows 3.x, the regedit.exe on your computer is the OLE link registry editor. Do not overwrite this.
Copy regedit.exe from the NT 4.0 CD-ROM and see tip 108 to associate the .REG extension with Registry Entries.