I too have this problem. Mod-PHP works but isn't allowed "write" privileges in the client's web directory. When I attempt to use SuPHP the error message Joomla's installer returns:
"An error has occurred:
Cookies do not appear to be enabled on your browser client. You will not be able to install the application with this feature disabled. Alternatively, there could also be a problem with the server's session.save_path. If this is the case, please consult your hosting provider if you don't know how to check or fix this yourself."
I know it's not a cookie problem. If I remember correctly, each clients' webroot (or perhaps root) should have a php.ini file that allows them to set the session.save_path as well as other variables for themselves, but I haven't been able to find the info that helped me solve this in the past.
Last edited by dc41; 18th November 2009 at 20:24.