BUG #4717: Installing PostGIS via StackBuilder gives an 'Error opening file' error

The following bug has been logged online:

Bug reference: 4717
Logged by: Andrew Smith
Email address: laconical(at)gmail(dot)com
PostgreSQL version: 8.3.7
Operating system: Windows XP
Description: Installing PostGIS via StackBuilder gives an 'Error
opening file' error
Details:

1. Install PostgreSQL. Use default settings for everything (I used 'English
- Australia for Locale but I don't think it matters).
2. At the end of the installation ensure that 'Launch Stack Builder' is
ticked, and click finish
3. Inside Stack Builder, select your PostgreSQL installation and click
next.
4. Expand 'Spatial Extensions' and tick 'PostGIS 1.3.5' and click next
5. Choose any mirror and click next
6. Click next and the installation files should start downloading. Once they
have download, click next.
7. Install PostGIS and use the default values for everything
8. Almost immediately, an error occurs:

Error opening file for writing:

C:\Program Files\PostgreSQL\8.3\bin\libiconv-2.dll

Using the unlocker program (http://ccollomb.free.fr/unlocker/) I can see
that pg_ctl.exe and postgres.exe both have locks on the file, which is why
it can't be overwritten. Stopping the PostgreSQL service removes the locks
on the file; however the PostGIS installation then fails because it cannot
create a PostGIS database.

At the moment, the workaround is to rename the DLL (after PostgreSQL service
is started) before installing PostGIS.