The problem is that the Windows 10 Anniversary Update broke Solidworks' ability to run C# macros.
there is an open critical SPR into Solidworks about this issue already. SPR #975920.
The first workaround is to roll back the offending Windows update, but based on the date of your post we're well past that point now.
There is a solution, however. Just today I received a patch from my VAR that restored this functionality (vsti_aide.msi). So, contact your VAR and ask nicely for the fix; it's way too large a file to share on the forum.
I can confirm Matthew Fry's comment that a patch has been provided. Contact your VAR, explain the problem, and tell them there is a patch available that you need. I installed it this morning and can now run C# macros.
There is an older thread that has been tracking the ongoing discovery and solution of the problem.