Hi KonstantinosS,
Thanks for getting back to me.
I know what you're referring to with the processing order. I have already made that change. There is an important distinction to note. I do not have any problems accessing / running PHP files. The errors specifically start to occur when trying to access a page within a WordPress site -- the index page of the WordPress sites have no problem loading. Again,
www.mydomain.com loads fine, but
www.mydomain.com/contact/ displays an NGINX error. There are many sites out there that have documented this issue. Here is a good example:
http://www.cult-of-tech.net/2011/11/wordpress-on-nginx-on-dreamhost/.
I went back and looked at that article and noticed that there are a number of wordpress plugins that claim to be able to solve this issue. I might give one of them a try and report back.