I am getting something similar, and I'm also installing the nagios 2.8 version. Here's some more stuff that may be helpfull to better help us.
In my apache error logs I'm getting this:
logs/error_log:[Sun Apr 01 23:17:39 2007] [error] [client Hidden] /usr/local/nagios/sbin/statusmap.cgi: error while loading shared libraries: libgd.so.2: cannot open shared object file: No such file or directory, referer: http://Hidden/nagios/side.html
So with that I thought perhaps libgd.so.2 was missing, so I did a locate for it, and got this:
I figured it was perhaps looking for it in the lib directory, so I made a link, "ln -s /usr/lib64/libgd.so.2 libgd.so.2" in the /usr/lib directory.
That didn't seem to do the trick. So I thought, perhaps it I needed to put it in the /etc/ld.so.conf file. Here's what I have now.
From here, I restarted apache and nagios, with no luck, and I have even recompiled nagios and that didn't seem to do the trick either. When I re click on status map, I still get the above error from my apache error log.
Oh and to add, all the appropriate cgi's are there, I'm only having trouble, thus far, with statusmap.cgi. I have deleted it, and recompiled , and it showed back up, so I believe that everything is there that should be.