Try the following:
Click Start --> Programs --> PostgreSQL --> Stop Service, then Start --> Programs --> PostgreSQL --> Start Service to restart PostgreSQL. If PostgreSQL does not start properly at this point and PT3 doesn't start working, click Start --> Find Files/Folders and search all types of files for a file named postmaster.pid. Once you find that file, delete it, then attempt to restart PostgreSQL as above, and it should start properly.
If it happens every time your computer starts, you should set PostgreSQL to start automatically when your computer boots. See
Setting up PostgreSQL to autostart for more information.