Aiuto Socialengine errore

Allora vorrei installare socialengine qui su altervista. ho già caricato tutto via ftp e mi ritrovo questo

Codice:

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Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, info@altervista.org and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

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Ho poi cancellato i file .htaccess dalla root e da /install e settato i permessi in 0777 ed esce questo

Codice:

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Your session configuration is incorrect and could not be automatically corrected. Please set session.save_handler=files and session.save_path=/tmp (or your temporary directory on non-Linux OSes.

For "cache_dir is not writable", set full permissions on temporary/cache

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con il logo di Socialengine

non so più cosa fare.
grazie in anticipo