(0x0000274D/10061) on Install

Hi, I am trying to install PostgreSQL on Windows Vista 32bit, I have deactivated UAC and the only kind of Firewall I have is Avast Home.
I am installing postgresql-8.3.6-2.zip, have also tried the 8.3.5.1.
I am installing with everything as standard.

During installation, during Activating Procedural Languages I get the error :
"Failed to connect to the database. Procedural languages files are installed, but are not activated in any databased. Could not connect to server: (0x0000274D/10061) Is the server running on host "127.0.0.1" and accepting TCP/IP connections on port 5432?"

And during Activating contrib modules, error:
"Failed to connect to the 'template1' database.Contrib files are installed, but are not activated in any databased.Could not connect to server: (0x0000274D/10061) Is the server running on host "127.0.0.1" and accepting TCP/IP connections on port 5432?"

Then PostgreSQL get "successfully" installed on my system.
But when I try to connect the default database or creating a new, it won't connect, and gives me the same error (0x0000274D/10061).

I really don't have a clue, but since it won't install it's most likely something to do with my configutation, maybe I have deactivated some necessary services etc?
Do you have an idea?

Best Regards
Joachim