Whenever you install a script on your website's root directory using Fantastico, it will add information to a file in your hosting account so you do not install a script over it, in order to prevent you from corrupting the site.
If you delete your script files and MySQL Database manually, this information will still be there and everytime you try to install a script in your public_html directory, you will get the following error:
|The installation can not be completed:
- You cannot install more than one script in the root directory of a domain.
Click on the browser's Back button to fix reported errors.