Seems that some of the installs are not allowing PostgreSQL to start automatically when you boot Windows. It should autostart, but for some reason, some installs fail. Here's how to set it up to autostart:
Go to your My Computer icon (its in Start or on your Desktop). Right click -> Manage.
You will see a window that looks similar to this:
Now, click on the Services and Applications icon on the left side of this window, and click on Services either below it or in the window on the right side. Now scroll until you find PostgreSQL database, right click -> Properties:
Now find Startup Type, and select "Automatic":
Click OK and close the windows out... You now have your server to automatically run each time windows loads.
NOTE: You do not need to do this as PokerTracker 3 will start the PostgreSQL service if it is not already running.