BUG #3802: cant install

The following bug has been logged online:

Bug reference:      3802
Logged by:          Craig
Email address:      craigabsiyeh@yahoo.co.uk
PostgreSQL version: 8.2
Operating system:   windows vista
Description:        cant install
Details:

Have tried to install the programme via the executable intilation file has
ran installation correctly up untill the point where it reads an error "user
"postgres" could not be created: Access denied!

Even if the name is changed this error will still come up but with the new
name replacing the "postgres" section of the error message. Can you please
help me, Regards Craig.