I just try to install the PostGIS 2.0.3 on PostgreSQL x64 9.1 on the Windows Server 2008 R2. I got the error message "Error openning file for writing" C:\Program Files\PostgreSQL\9.1\bin\libiconv-2.dll. Should I click "Abort", "Retry" or "Ignore"? Thanks. :)
You cannot overwrite libiconv-2.dll because it has been locked by postgres.exe. So, first you must stop the postgresql-9.1 service from your control panel/administrative tools/services. Second, restart the PostgreSQL service, rename libiconv-2.dll to libiconv-2.old and then proceed the PostGIS installation.
I had this problem due to user permission errors on Windows Server 2008 R2.
It might not like that your Domain user is also an admin user. It might expect a local admin user instead.
I remember creating a local (not a DOMAIN user) user with admin rights or used an existing account with admin rights then logged in with that local admin user and installed that way.
Then logged out and back in with regular user/domain account.