BUG #5653: Error reading the C:/Program Files/PostgreSQL/8.4/data/postgresql.conf"

The following bug has been logged online:

Bug reference:      5653
Logged by:          Kesavan
Email address:      kesavan@emmeskay.com
PostgreSQL version: 8.4.0-1
Operating system:   Windows
Description:        Error reading the C:/Program
Files/PostgreSQL/8.4/data/postgresql.conf"
Details:

This issue related to Bug #5253.

While Installing Postgres, Warning message thrown as

"Problem running post-install step.  Installation may not complete
correctly.
  Error reading the C:/Program Files/PostgreSQL/8.4/data/postgresql.conf"

If I proceed the installation it turns out the data directory is completely
empty.  During the install, I did_not_ un-check the box asking if I wanted
to "Install pl/pgsql in template1 database", so it should have been in there
as well.

I ran the installer while logged into the Administrator account. So
absolutely no issue of Read/write access in "C:/Program
Files/PostgreSQL/8.4/data/postgresql.conf" file.

After few attempts, I was able to install without any issue in the same
system with same user and the same directory path.

So I want to know, what are the root causes for this issue. How to prevent
this issue? Also if the issue happens, is there any manual procedure to
populate the data (dictionary) folder?