VMWare host that hosted the session state server* failed. Due to a configuration issue that session state server did not automatically restart on another host (in effect negating the built-in redundancy).
Steps taken to address this:**
1. We took the failed VMWare host out of our production load.
2. We have redistributed key processes to other VM Hosts.
3. We are working with VMWare to implement a more robust redundancy for our session state server.
*Session state server: Server used to track login activity between multiple servers for load balancing.