This error message occurs as a result of another program not allowing PostgreSQL to install properly. The solution is to uninstall PostgreSQL completely and reinstall it in Safe Mode. To boot into safe mode, click Start --> Run type “msconfig” and hit OK. Under the “Boot.ini” tab, check “Safe boot” and “Network”. Click Apply, then OK, and restart your computer. It will boot automatically into safe mode. Double click on “My Computer”, then browse to your PostgreSQL directory and delete it (the default is C:\Program Files\PostgreSQL). Click Start --> Run, type “cmd” and hit enter. At the command prompt type “net user postgres /delete” and hit enter. Exit the command prompt, and proceed with the PostgreSQL installation. Once the PostgreSQL installation has finished, go back into the msconfig window again as directed previously, and uncheck the “Safe boot” checkbox. Then reboot your computer and PostgreSQL will be properly installed.
If you're in Windows Vista you'll want to install
PostgreSQL 8.2.7, otherwise you'll want
PostgreSQL 8.3.1, and you
will need to remember the password for the postgres user, so make sure not to lose that. (You'll need to put it in when you start PT3.)