I had an issue with Nagios on Gentoo, and it the ebuild putting the config 
file in the wrong directory.
Check this out:

http://bugs.gentoo.org/show_bug.cgi?id=103060

HTH,

-- 
Bruno Lustosa, aka Lofofora | Email: bruno@lustosa.net
Network Administrator/Web Programmer | ICQ: 1406477
Rio de Janeiro - Brazil |