Solutions:

- If you have multiple (Live) sites in your NetCommunity environment, make sure they are not using the exact same Primary URL.
To verify, do the following:

1. Log into NetCommunity as an admistrator
2. Go to: Administration > Sites & Settings
3. If you have multiple sites listed in the left panel, click on each and review it's Primary Site URL
4. If more than one have the same Primary URL and they are live, you will need to change/update one or more of the Primary URLs
5. For example append a "/path" to the duplicate Primary site URLs like this: www.YourSiteName.org/archive
   1. In the example above, "/archive" is the path added to the Primary URL. This can be anything you want it to be. 
6. Save
7. Repeat until all sites have a unique Primary site URL.

- If that does not work, the problem is likely related to a recent DNS change in the network. Try the command ipconfig /flushdns from a windows powershell or command line on the NetCommunity web server.  This will force the web server to propagate the changes and the site should begin to load correctly.