Renaming ?
The version bundled with Fantastico is not the latest version, however both use an .htaccess file, and could have the same problem depending on how your server is setup.
It mainly depends on which version of Apache your server runs.
http://www.dew-code.com/content/view/14/25/
Also, keep in mind lately it seems servers are set to cache .htaccess files, as well as your browser caching pages...
So if you try uncommenting one line in the .htacess , like
# ForceType application/x-httpd-php
SetHandler application/x-httpd-php
View your install, if the error persists, wait a minute, then hold shift and reload/refresh the page in your browser, to force your browser to fetch a fresh copy.
If the error still occurs, try the next line in the .htaccess by toggling the comment
#ForceType application/x-httpd-php
#SetHandler application/x-httpd-php
SetHandler application/x-httpd-php5
Grabbing the latest version will not magically detect which syntax to use, but it does add more features to the script.