It appears that the Windows 10 64 bit version, when updated to 1803 will no longer allow Mach3 to use its DLLs, which causes Mach3 not to load!

Solutions:
1) if using 64 bit Windows 10, don't let it update to 1803, or revert it if it does.
2) It appears that this is not an issues with 32 bit Windows 10 (at least for the moment).
3) Windows 7 should be immune to this problem.
4) Mach4 is safe from this problem.

Here is a post on the MachSupport forums covering this issue.

https://www.windowslatest.com/2018/05/09/windows-10-kb4103721-bugs/

Microsoft may relent and undo this change, but they may stay the course and force it as the way it will be.

Andy