Error Message 1500 when Installing Boulevard

Error message 1500 usually occurs when more than one instance of the Windows installer is running at the same time.

1.  Ctrl  +  Alt  +  Delete  to launch the Windows Task Manager.

2. Select any Windows installers that are running, then click End Task.

3. Repeat step 3 until there are no Windows installers running.

4. Restart the computer, then proceed with installing Boulevard again.