I've been trying to play MM9 on my PC, and the game won't even launch. I found the fix, and wanted to share it here.
I have the old CD version of the game. The reason for the crash on launch is a missing Windows Service called secdrv.
This was a form of DRM CD-check popular around 2003-2008. Windows stopped supporting it with Windows 8, and completely eliminated it in Windows 10. I included a link below to the Microsoft forums where people are talking about it.
It is currently impossible to play the CD version of MM9 in Windows 10. The solution is to acquire a digital download version of the game that has no CD-check.
I hope this helps somebody else avoid wasting a whole day searching for the ability to launch an old game post-Win10 upgrade. As I type this, my download from GOG is running