Error installing postgresql-8.2.4 on windows 2003 server

I have been successful in installing to Windows 2000 but when installing the
binary installation "postgresql-8.2.msi" as a service, I receive the error

The program "postgres" is needed by initdb but was not found in the

same directory as "C:/Program Files/PostgreSQL/8.2/bin/initdb".

Check your installation.

I have checked and found both the postgres.exe and initdb.exe files in the
directory "C:/Program Files/PostgreSQL/8.2/bin/initdb".

Does anyone have any ideas what the problem could be?

Hugh