If you want to open a machine or User Defined Component in Machines Simulator v.3.x, created with M.S. version 2.x you must follow the next procedure:
1) Download the Machines Simulator version 2.5 (available in Nirtec website, downloads section -> Previous Versions).
2) Install it (but take care and do not install in the same folder than Machines Simulator v.3) and copy the license file (license.lcs) in the new program location.
3) Open your machine file or Used Defined Component and save it normally.
4) Now, open Machines Editor v.3.X and from menu toolbar choose Tools -> Convert Files.
5) Select the file to convert pressing the button.
Now you can open the fles normally!.