Forgot some important info. PT3 connects without any problems.
Furthermore I tried the following:
unable to login to database (PT3_xxxx_xx_xx_xxxxxx) - reason:could not connect to server:connection refused(0x0000274D/10061) Is the server running on host "localhost" and accepting TCPT/IP connection on port 5432?
First thing to try is to restart the postgres service.
Start -> Programs -> Postgres -> Start Service.
If this doesn't help, try a reboot.
Update: try this;
Try stopping the service (Start -> Programs -> Postgres -> Stop Service), running a search on your computer for postmaster.pid and then deleting that file, then restarting the service and see if that helps.
Note that you may need to turn on 'View hidden files and folders', and the file seems to be in the folder './Program Files/postgresql/<version>/data'
See also: viewtopic.php?f=17&t=6332#p38285
postmaster.pid didnt exist