pg_ctl issue

I installed PostgreSql on Window2003 server under an administrator account.
I can start postgresql from Windows Service.
But when run the following command, it fails:

C:\Program Files\PostgreSQL\8.3\bin>pg_ctl start -D "C:\Program
Files\PostgreSQL\8.3\data"
server starting

C:\Program Files\PostgreSQL\8.3\bin>FATAL: postgres: could not locate
matching postgres executable

And the following command works well:

C:\Program Files\PostgreSQL\8.3\bin>pg_ctl stop -D "C:\Program
Files\PostgreSQL\8.3\data"

Thanks.

Jack