As you mentioned in your comment above, it looks like installation issue.
Microsoft recommends that you add the Microsoft Dynamics CRM server to the PrivUserGroup group when you install the Microsoft Dynamics CRM server. If the server is manually removed from the group or if the server was not added during the installation, you experience the problem that is mentioned in the "Symptoms" section in the link below:
However this KB article is for 4.0 but it could be the same issue with 2013 as well. Worth reading.
Update
Also its worth checking application pool.