On some Snow Leopard computers the folder gets set with the wrong permissions.
To correct the permissions:
- Open your Macintosh HD.
- Open the Applications folder.
- Highlight (single click) the Screenwriter 6 folder.
- Click on File > Get Info (CMD+I) to bring up the information for that folder.
- Open the Sharing and Permissions section.
- Unlock the padlock if necessary.
- Select "Everyone" from the list.
- Change the permissions to Read & Write.
- Close the window.
You should now be able to access the Screenwriter 6 folder.