I have just installed gitlab and nginx on Ubuntu LTS 12.04 using this guide: http://blog.compunet.co.za/gitlab-installation-on-ubuntu-server-12-04/

I installed this on another server last night and had absolutely no problems with it (sort of a test run to see how long it would take to get going). I am not getting any errors when restarting gitlab or nginx with /etc/init.d and my error logs are empty. The only thing I know of to go on is the vhost config:

    upstream gitlab {
            server unix:/home/gitlab/gitlab/tmp/sockets/gitlab.sock$
    }

    server {
            listen localhost:80;
            server_name gitlab.bluringdev.com;
            root /home/gitlab/gitlab/public;

            # individual nginx logs for this gitlab vhost
            access_log /var/log/nginx/gitlab_access.log;
            error_log /var/log/nginx/gitlab_error.log;

    location / {
            # serve static files from defined root folder;.
            # @gitlab is a named location for the upstream fallback$
            try_files $uri $uri/index.html $uri.html @gitlab;
            }

            # if a file, which is not found in the root folder is r$
            # then the proxy pass the request to the upsteam (gitla$
            location @gitlab {
            proxy_redirect off;
            # you need to change this to "https", if you set "ssl" $
            proxy_set_header X-FORWARDED_PROTO http;
            proxy_set_header Host gitlab.bluringdev.com:80;
            proxy_set_header X-Real-IP $remote_addr;

            proxy_pass http://gitlab;
    }

}

If there's any other information that would be helpful, just let me know and I'll get it up asap.