Recently, Windows 10 released a "feature upgrade" that updates your version to 1803. This new version was incompatible with Mach3. It is recommended to use Mach3 on a dedicated computer that is offline and is not susceptible to automatic updates, but that is not always plausible.
To overcome this issue, we have added a patched version of build V3.043.062 (created by one of our partners) that is now the default download for Mach3 onto our website, this will run in Win10 V1803.
-Mach4 has not been affected by this update.