Installed Apache 2 with mod_fastcgi and your apps are failing? Did you change the default Apache user and group? The clue will be in these error lines in error_log when you restart the server.

[Sun Apr 03 15:06:09 2005] [error] FastCGI: access for server (uid 501, gid 501) failed: read not allowed
[Sun Apr 03 15:06:09 2005] [error] FastCGI: can't create dynamic directory "/usr/local/apache2/logs/fastcgi/dynamic": access for server (uid 501, gid 501) failed: read not allowed

Just go into your logs folder and chown -R user:group * replacing 'user' and 'group' with the entries in your httpd.conf file. Easy. Restart server, and your fastcgi apps will work.