BUG #4988: Installer fails when creating password

The following bug has been logged online:

Bug reference: 4988
Logged by:
Email address: jeremy(dot)rosenburg(at)gmail(dot)com
PostgreSQL version: 8.7.3.1
Operating system: Windows XP
Description: Installer fails when creating password
Details:

I was installing for the first time and entered a password that contained
special characters #$% for the postgres user. The installer blew-up after
the user was created but now I'm totally stuck since it's not obvious how to
remove or change the password of the postgres user that was created just
before the installer failed. Uninstalling won't clean it up and
reinstalling keeps finding the user with a password that causes CREATE~1.EXE
to abort during install.

So, I'm not forming a very positive first impression of PostgreSQL