I received the error message "Serial in use."
First - do you have the latest version of Circle² installed?
You can always find the latest Circle² installers here.
Most error messages can be quickly resolved by updating your software.
. . .
If that doesn't work...
Each Circle² license comes with three activation slots, allowing you to installation and activate Circle on up to three computers at one time.
Once your activation slots are filled, you may encounter the "Serial in use" error message.
But don't worry! Just drop us a line at email@example.com with your activation code and we'll reset your activation slots right away.
. . .