psql: server closed the connection unexpetedly

Hi,

I can't connect to a new installation of PostgreSQL 8.1 on a XP SP1 laptop.

Im trying to connect using psql in the laptop's command prompt. i keep
getting the following error message:

psql: server closed the connection unexplectedly
this probably means the server terminated
abnormally before or while processing the request

I can start & stop the postgresql service with no problems. and if i try
to connect while postgresql is not running i get the expected error:

psql: could not connect to server: Connection refused (0x0000274D/10061)
Is the server running on host "???" and accepting
TCP/IP connections on port 5432?

the laptop has a trendmicro firewall installed, but this is set to allow
all connections from the localhost. plus i have other XP machines with
the same setup and postgresql installation working perfectly.

has anyone else ever come across the problem? or any suggestions as to
what the problem may be?

thanks in advance

phil..