Did you install PostgreSQL? Click Start --> Programs --> PostgreSQL --> Start Services to start the PostgreSQL service. If you don't see the "Start Services" link or the PostgreSQL folder then you don't have PostgreSQL installed and you will need to download and install PokerTracker 3 Beta 26
Full Install (which contains PostgreSQL) from our
download page.
If you have PostgreSQL installed, check to make sure that you have UAC disabled (
tutorial), and make sure that your anti-virus/firewall programs have exceptions built in for pg_ctl.exe and postgres.exe (both in the C:\Program Files\PostgreSQL\8.3\bin\ directory) as those programs could cause problems for PostgreSQL if configured aggressively.