Sometimes when you register the product it asks again to re-enter the registration number. When this happens the second time you get a message that the product is already registerd. THis happens when the local user does not have read/write permissions to the local system registry.
ISSUE: Registration is not sticking
SOLUTION:
Run ACT as administrator to register the product by following these steps:
Close ACT!
Right-click on the desktop shortcut to open the popup menu
Select "Run as Administrator"
If you are NOT the local administrator then ACT will request you to enter your administrator password. Please contact your IT department for the administrtor password.