That's 'cos it's not an "open" file on the Core itself. It resides in the WinPE image.
1 - Go to (default path) - "C:\Program Files\LANDesk\ManagementSuite\landesk\vboot\"
2 - Open up "LDVPE1.IMG"
You'll need a tool like winimage (www.winimage.com) for this.
3 - go into the LDCLIENT directory inside the image
4 - Voila ... DRVMAP.EXE in all its glory.
LANDesk EMEA Technical Lead.