Error:Unable to install because of tryout

Issue
Premiere Pro produces one of the following error messages:
 * "Setup is unable to proceed because a tryout version of Premiere Pro 1.5 is installed on this computer. Setup will quit now"
 * "Premiere Pro is unable to install because a tryout version of Premiere Pro is installed on this computer"

Solution

 * Re-install the tryout version and then uninstall it using the Windows Control Panel.