If you had installed WordPress on your server and you deleted it sometimes you may get this error after trying to install it automaticaly again.
You cannot install more than one script in the root directory of a domain
That usually happens if you deleted older WP partly by hand and partly automaticaly with Fantastico, Quick Install or some other Cpanel script. At Install WordPress 2/3 part, the installation just can not be completed. Continue reading WP: You cannot install more than one script in the root directory