Be sure you have the latest version of Cythera - 1.0.4
Go to the Cythera folder and select the application icon by clicking on it one time, then go to the File menu to Get Info. If it is any version prior to 1.0.4, go to http://www.ambrosiasw.com/games/cythera/ and download the latest version.
Before launching the update, throw out the preferences for Cythera. Go to your System/Preferences folder and drag the Cythera Preferences file to the trash. Then launch the game.
If problems persist or you are already running the latest version, read through the rest of the FAQs for currently known issues and workarounds.
For further assistance please contact our Technical Support.