installation problem with postgres password

Hi all,

i am trying to install postgres on a new machine with win 7. i tried
two different versions (9.0.4 and 9.1.4) and the problem is the same

when i run installation it asks me to provide a password for superuser
and service account,

i tried to enter numerous options, including leaving it blank - the
setup hangs for a minute or two and then show a warning message:

"The password specified does not meet the local or domain policy.
Check the minimum length, password complexity and password history
requirements."

i also tried to run it as administrator, no effect.

any ideas?

thank you