1/ Is it possible to write on a NTFS partition?
No, the free version of NTFSDOS is read-only.
2/ If I boot just with freedos, then I launch VC which bugs when I try to read T: and U:.
Do you have problems doing a "dir t:" or "dir u:"
3/ When I launch "Offline NT password ...", I just get the message "ISOLINUX 2.00 2002-10-25" and then it hangs. I use successfully this option on an old version (2.x) of UBCD.
Do you think it is possible to jump to the console at the main menu and try "bcdw boot /images/offline.iso"?