Vista 64 gives us nothing but trouble.
If you get the message "Beta has expired" then there's an old Beta version still hiding in your system somewhere. It could be in a System32 or SysWOW directory. Try to find it and delete it.
After that, right-click on the new MA3 icon which the installer has (hopefully) placed on your desktop. Choose "Install", and you should be able to install it as your screensaver.
|