Ntvdm.exe is the Windows NT Virtual DOS Machine. Virtual DOS machine (VDM) is a technology that allows running legacy DOS and 16-bit Windows programs on Intel 80386 or higher computers when there is already another operating system running and controlling the hardware. This is used by Windows to allow DOS applications to run under Windows NT-based operating systems (2000, XP, Vista, 7).
This process will be located at c:\windows\system32\ntvdm
This process will be located at c:\windows\system32\ntvdm