Errore in apache

Ho installato apache 2 e creato un’applicazione rails.
In modalita cgi funziona correttamente (anche se molto lento); attivando
fcgi modificando .htaccess il browser restituisce questo errore

Service Temporarily Unavailable

The server is temporarily unable to service your request due to
maintenance downtime or capacity problems. Please try again later.

Se vado a vedre il file di log di apache vedo questo errore:
[Fri Mar 30 00:47:06 2007] [notice] mod_fcgid: process
/var/www/novel/public/dispatch.fcgi(6485) exit(server exited),
terminated by calling exit(), return code: 255
[Fri Mar 30 00:47:09 2007] [notice] mod_fcgid: server
/var/www/novel/public/dispatch.fcgi(6486) started
[Fri Mar 30 00:47:10 2007] [notice] mod_fcgid: server
/var/www/novel/public/dispatch.fcgi(6487) started
[Fri Mar 30 00:47:10 2007] [notice] mod_fcgid: process
/var/www/novel/public/dispatch.fcgi(6486) exit(server exited),
terminated by calling exit(), return code: 255
[Fri Mar 30 00:47:13 2007] [notice] mod_fcgid: server
/var/www/novel/public/dispatch.fcgi(6488) started
[Fri Mar 30 00:47:13 2007] [warn] mod_fcgid: can’t apply process slot
for /var/www/novel/public/dispatch.fcgi
[Fri Mar 30 00:47:16 2007] [notice] mod_fcgid: process
/var/www/novel/public/dispatch.fcgi(6488) exit(server exited),
terminated by calling exit(), return code: 255
[Fri Mar 30 00:47:16 2007] [notice] mod_fcgid: process
/var/www/novel/public/dispatch.fcgi(6487) exit(server exited),
terminated by calling exit(), return code: 255