If you have a particularly old version of Flying Logic, it might not like your newer OS. And sometimes, when you download a new version, your system keeps pointing at the old one.
To solve this problem, delete ALL executables you can find for Flying Logic on your system, download a fresh, up-to-date copy, and you should be good to go.
If for some reason that doesn't work, drop us a line at support@flyinglogic.com.