The following bug has been logged online:
Bug reference: 4104
Logged by: alex
Email address: shaselai@yahoo.com
PostgreSQL version: 8.3.1
Operating system: windows XP
Description: Uninstall/remove not working correctly
Details:
I recently uninstalled 8.3.1 and I deleted the remaining files not removed
from the uninstaller. I then proceed to install 8.3.1 again using same user
info as before. The installer proceeded to install until the creation of the
user and it says "user postgres already exists" and then rollbacked the
install. If I install using different username like postgres1 then
everything's fine. Maybe this is not a bug but there is a file i am suppose
to remove but missed?