Win32 8.3.3 install fail (sufficient privileges to install system services).

I did installed 8.3.1 on WinXP Prof. and all was ok.  After that
successful install I have tried to install 8.2.x without success several
times on the same workstation.

Today I have tried to install 8.3.3 and I have stuck on the same error:

===============
Service 'PostgreSQL Database Server 8.3' (pgsql-8.3)
could not be installed.  Verify that you have sufficient
privileges to install system services.
===============

After that, you can _only_ CANCEL install.  Of course I have sufficient
privileges because I am on Administrators group.  Moreover I am
installing with the same user I have installed 8.3.1 only two days ago.

Any idea ?

Greetings.