well; too bad: I can't get your attached file ... that could have helped a lot
and too bad also that nagios is not very helpful. Usually, when there's an error, it just points to the line that causes the difficulty.
Anyway, firstly, you can try the command:
nagios-dir/bin/nagios -v nagios-dir/etc/nagios.cfg
It may be a bit kinder and help you... but I'm not really hopeful on this one!
Anyway, something that may help you:
you should get rid of all your personnalized config files.
ie: try to start nagios with the minimum (1 hostgroup, 1 host, 1 service); just get rid of everything else.
Then, once you get nagios going, add your own config one by one (like 1 host at a time); this will help you troubleshooting the issues.
And if it still doesn't work, try to post here your first 100 lines of nagios.cfg, and your config files (don't know the post limit, but I hope it will fit :))