First you didn't answer the previous question:
>Does it work when you use runas
This question was asked to pin point the problem: is the problem with the
postgres windows user set-up or is it with the third party tool?
I personally have used "runas" to run windows batch files with PostgreSQL
and it works fine for me, therefore I would suggest that you have either a
problem with the postgres user account or with the third party tool "runasv"
I use a third party tool named "cpau"
(http://www.joeware.net/win/free/tools/cpau.htm) to automate batch processes
without password prompting and again I have no problems with PostgreSQL -
therefore please try one of these options before blaming PostgreSQL. If any
one of these options work then the problem will be with your third party
tool "runasv"
Regards
Donald Fraser