Acrobat 10.1.16 Stops working when using Preflight

I have Acrobat 10.1.16 installed on two different computers; one is Windows 7 Enterprise Service Pack 1 and the other is Windows 10 Pro with all updates current.

I received two files from a customer: Acrobat just sits there apparently doing nothing When I preflight them on the Windows 7 machine. Acrobat crashes (Stops Working message) when using preflight on the Windows 10 machine.

Both of the files contain heavy use of image masks, for what that is worth.

Enfocus Pitstop does preflight both files.

How do I proceed to debug this?

Thank you,

David