PokerTracker

I've had poker tracker for over a year and everything has been working properly. Today I opened it and the first thing it says is "PokerTracker was unable to connect to any PostgreSQL Database. Please make sure you have PostgreSQL running" Then it has a link to this forum that wouldn't open. When Poker tracker opens, in the box where it has all the players names it says "Unable to connect to database: PokerTracker 3 database". Even though this was happening i was still able to play and import hands but it wouldn't show anything in the database. So I uninstalled PostgreSQL 8.3 and reinstalled 8.4 and its still not working.

When you re-installed did you follow this guide? Postgres installations need to be done carefully.
When you start posgres (Start > Programs > Postgres > Start Service) do you see any postgres processes in Task Manager > Processes?

What firewall do you use?
Did it update recently?
Try disabling it temporarily while you start up.