Xubuntu - application state being unintentionally restored on restart/shutdown

I'm running Xubuntu 14.04 with updates done today. After the update finished it asked to restart to finish the update, so I did.

Once the system booted back again, I've noticed that all the applications that were open prior to the restart, are back to the same state they were prior to.

So I made sure that I closed all running applications ( Firefox, Thunderbird, VMware Workstation, and Thunar file manager), and I tested with restarting, and shutting down the computer, and results were the same.

All were back running to the same state that they were prior to testing.

I haven't changed any setting, modified any startup file, or anything similar. What is causing this, and how can I solve it.