Version 5.2.5 and earlier - A rare bug:
When installing for the first time and selecting the screensaver in the system preferences, you must have internet connectivity.
If you do not have internet connectivity, the screen saver might stall when it closes down.
Then, you will need to Force-Quit the system preferences.
This affects only the first installation and first run; the screen saver operates fine without needing internet connectivity at all.
The bug does not affect the re-installation of newer versions over an existing one. It only happens during the first installation.
This rare bug will be investigated and fixed in the next version.
In the meantime, just make sure you are connected to the internet when you first install the screen saver and configure it for the first time.