BUG #2476: Instalation problem

The following bug has been logged online:

Bug reference: 2476
Logged by: Alexander Cordeiro
Email address: alexandergc(at)pop(dot)com(dot)br
PostgreSQL version: 8.1
Operating system: Win XP
Description: Instalation problem
Details:

I'm trying to install PostgreSQL 8.1, for the first time in my computer.
When the progress bar indicates that all the files have been copied, a
messagem comes up informing that the user (alexandergc) I've chosen already
exists.

Then I tried other names (postgres, posjava, xyz) and still got the same
result. Note I said it's the first time I'm trying to install. I tried to
run a REGCLEANER to clean anything from former installations, but nothing.

I hope you can help me.
Thank you,
Alexander.