<x-charset iso-8859-1>> Are you sure? Utilities like that normally do the lowest-level raw disk access functions (Int 13H), as opposed to partition access functions (Int 25H and 26H). and don't care what sort of file system is on the disk, or even if there is anything at all on the disk. That was my first reaction too, but... To read/modify/write/verify/modify/write/verify the sectors, which is what this app presumably does in order to test the surface without destroying the contents permanently, you have to be able to rely upon the sector CRCs. For those to be valid, the disk must be formatted. If the format used is NTFS, Int13/25/26 may not handle it correctly... If it was a disk recovery system (like the old Norton Utilities), it might easily make n retries on any sector which returns an error, and write out the most common variant of the n tries (potentially 'fixing' the bad sector during the write process). That may what they'll need to do to make it work with NTFS, but there's a possibility that this might actually wreck the NTFS formatting if, for instance, the CRC is located differently or calculated differently in the extra bytes at the end of the sector. Just guessing, as I don't have a disk to sacrifice to this test :-) D. - Turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for list instructions. </x-charset>