I recently installed SharePoint 2010 on my development environment and as part of my development, I commonly use the Default Web Site to host my applications that require IIS. Furthermore, I continued to believe that I could use the Default Web Site because when I installed the Standalone instance of SharePoint 2010, it automatically provisioned another web site for me called SharePoint - 80.
Well, unfortunately, as I discovered, SharePoint 2010 provisions the Default Web Site (in some unknown manner to me). I imagine that it installs some type of SharePoint Filter/SharePoint ISAPI on the Default Web Site.
Well, the unfortunate consequence of this, is that any web application development which attempts to use the Default Web Site for development will receive network error messages while attempting to browse to any content hosted beneath the Default Web Site.
So, what is the remedy? Well, of course, simply create a brand new website in IIS! After doing this, my development web sites immediately began working again.
Maybe, in the future, I will get a chance to figure out how to continue to use the Default Web Site alongside SharePoint for development, but for now, creating a separate web site works for me.
Hopefully this information will help others who have struggled with this problem as well.