You must be running NT 4.0. At the end of this fix, you will have applied Service Pack 3 (or later).
Install a maintenance copy of NT (preferably on a different drive) and call it NTMAINT. You will need 486160MB of free space but the folder may be compressed afterwards. If you don't intend to keep NTMAIN after the fix, first:
attrib -r -s -h c:\boot.ini
copy c:\boot.ini c:\boot.bak
Apply SP3 (or later) to NTMAINT.
Do an update install of your original installation.
Boot to NTMAINT (first entry on the boot menu) and:
copy <Drive:>\NTMAINT\System32\Samlib.dll <Drive:>\WinNT\System32\Samlib.dll
copy <Drive:>\NTMAINT\System32\Samsrv.dll <Drive:>\WinNT\System32\Samsrv.dll
copy <Drive:>\NTMAINT\System32\winlogon.exe <Drive:>\WinNT\System32\Winlogon.exe
Boot to the original install (third menu item)
Reapply the latest Service Pack.
If you intend to delete NTMAIN:
attrib -r -s -h c:\boot.ini
copy c:\boot.bak c:\boot.ini
attrib +r +s +h c:\boot.ini
and then delete NTMAIN
If you want to keep NTMAIN, use Control Panel / System / Startup/Shutdown to change the default to your original install. Then:
attrib -r -s -h c:\boot.ini
Edit boot.ini at rearrange the entries and change the text of the NTMAIN entries to NTMAIN. Then:
attrib +r +s +h c:\boot.ini
