BUG #6464: Installer (postgresql-9.1.2-1-windows-x64.exe) doesn't work

The following bug has been logged on the website:

Bug reference:      6464
Logged by:          Lucian Naie
Email address:      lucian.naie@gmail.com
PostgreSQL version: 9.1.2
Operating system:   Windows 7 Ultimate SP1, x86, 64 bit machine
Description:=20=20=20=20=20=20=20=20

I get an error dialog saying:
"Unable to write inside TEMP environment variable path."

I have checked the forums for solutions and tried everything.
I'm running it from an admin account.
This is hardly believable, especially now when I'm prospecting a DB server
for a demo project meant to get funding.
Did anyone tested this?