Package dropping scripts tend to be unreliable for many packages, I'm afraid.
My suggestion is to ...
1. Stop AOLserver (if it's currently running)
2. at the shell command line: dropdb your-acs-db;createdb your-acs-db
3. Restart AOLserver
4. You'll see the initial install page for all of OpenACS. Reinstall the core, restart, and try installing file-storage now, on this fresh instance.
Hope this helps!