SharePoint 2013 - Cannot Delete or Save Documents

Working on the new SharePoint 2013 and we were running into different issues. Could not save or delete documents and we received the following "Unexpected response from server. The status code..." error when replying on a list/discussion.

Looked like a permissions or authentication problem to me. Doing a trace after a save or delete I saw that it was cycling between the HTTP request and redirect to login. Changing the authentication settings on the site in IIS fixed the problems.