Net Express and Windows 10 comes with a few challenges.
Some of the things I've had to do with our developers that run Windows 10:
Set the environment varaiable MFOLECL_NO_THREAD_INIT with a value of Y - We had to do this only on a few machines (Cause unkown)
Delete the nxdebug.~ds found under C:\Users\The Windows Username\Documents\Micro Focus\Net Express 5.1\WORKAREA - This resolves 114 errors when you hit a Debugbreak during animation and NetExpress wants to load the source code
Delete the HKEY_CURRENT_USER\SOFTWARE\Micro Focus\NetExpress\5.1 - This key recreates itself but you'd loose your preferences. This also can resolve 114 errors when breaking into animation.
What have you got in your manifest for your executable?
Does it support Windows 10 themes?
msdn.microsoft.com/.../bb773175(v=vs.85).aspx
If you upgrade to Windows 10 from an older version of Windows it corrupts the Net Express license.
These are a few things I have come across getting Net Express working on Windows 10.
Perhaps one of the above will resolve your problem.
Neil