Problems connecting to Windows-based Postgresql
Here are the steps of troubleshooting I would recommend:


From the local machine try the following.  If they work you know the issue is not PostgreSQL.  If they don't work then you know your issue is local to the machine.


psql -h localhost -p 5433 
psql -h [external ip] -p 5433
If the latter fails, try temporarily disabling all firewalls and trying again

Now if that works the next step is to troubleshoot the network.  Traceroute may be helpful here.  Also try connecting to any other open ports using other software and make sure that works.  From there, you may be able to figure out exactly where the packets are being dropped.