postgresql as windows 2000 service problem

In event log it says something like "unable to find exe file"
I have enabled logging in postgresql.conf but nothing else is logged.
When I start postgres as user 'postgres' with 'pg_ctl start', it logs
a lot of things: timezones, environment variables etc.

I don't know whice exe it means. It cant be the bath because
env system variables PATH and PGDATA are ok.

To which files/folders should user postrges have rights; I have created
user postrges as a typical user (admin or power user is not possible to
run pg_ctl) and gave him the log on as service right.
Also user postgres is the owner of the folder c:\postgres (with any subfolders).

I also tried 'pg_ctl register -U postgres -P xxxxx -o "-i" but the
same error.

The only thing that bothers me is that in windows xp it runs fine.