The application isn't compatible with Windows 7 or Windows 8.1. At the time of release Modret was made compatible with 95, 98, 2000. To run it in Windows 7, because Windows 8.1 is out of the question, you will need to install Windows XP Mode. Download the package and install it, then you should be able to run application that was created for older versions of Windows. You should also visit the tutorial guide offered by Microsoft on how to install XP Mode in Windows 7.