Wow! Thank you for posting an answer to your own problem! You probably saved me hours worth of work.
I too just installed Nagios on a Solaris 10 box, and after hours of working to make it run in Solaris I was so frutrated when I started seeing errors on several pages. I ran into this error when trying to look at the map and a few other pages. It was the only thing I couldn't seem to figure out, as I had /usr/local/lib my LD_LIBRARY_PATH environment variable. Nagios is difficult to get working on Solaris SPARC (took me 15 minutes to get up & working in Ubuntu), but now I think it's finally working as it should. Now I can finally start working on setting up monitoring services.
Simply running the command "crle -l /lib:/usr/lib:/usr/local/lib" fixed it for me. I didn't even have to recompile.
If you don't mind me asking an unrelated question, have you found check_by_ssh or NRPE to be more beneficial for monitoring Solaris systems? I could use either one, but I'm leaning towards check_by_ssh since that seems like it might be more convenient.