I recently acquired an NT4 system from a friend and removed the secondary hard drive to copy it. The file system was not recognized by Windows 2000 or Windows XP -- it appears to the OS as "not formatted" although it is. I even tried mounting it under Linux Knoppix because it was suggested that Knoppix is able to read HPFS (which I suspect might be the File System). It would not mount. The NT4 machine reads the disk without problem or error. The drive is an IBM Deskstar, about 49 GB if I recall. I do not know the origin of the drive, but it could have been used in a business system before being installed in my friend's machine. How can I find out what the file system really is, so I can understand this mystery? Or does anyone have a logical explanation of why this drive is "unreadable" outside of the NT4 box?