This article was previously published under Q90565

When you install Microsoft MS-DOS 6 or later Upgrade, Setup adds one the following lines to the [386Enh] section of the SYSTEM.INI files if you install the Windows-based programs.

   ;======== MS-DOS 6 Setup Modification - Begin ========
   device=C:\DOS\VFINTD.386
   ;======== MS-DOS 6 Setup Modification - End ========

   ;======== MS-DOS 6.2 Setup Modification - Begin ========
   device=C:\DOS\VFINTD.386
   ;======== MS-DOS 6.2 Setup Modification - End ========

   ;======== MS-DOS 6.21 Setup Modification - Begin ========
   device=C:\DOS\VFINTD.386
   ;======== MS-DOS 6.21 Setup Modification - End ========

VFINTD.386 is a virtual device driver (VxD) that adds support to Windows to prevent conflicts between multiple virtual machines.