Hi folks The problem is solved now. Actually, a BIOS upgrade solved the problem.
Details:
The board is a Asus A3M78-Pro with a AMD 5050e Athlon64 Dual core CPU. Bios
version was V0902 with with it was originally shipped.
Asus bios notes for that board say that with Version 11xx a bug was fixed
which causes Vista's internal system time go too slow. Bingo. Linux seemed to
be affected as well, so after upgrading to latest 13xx version, ntp behaves as
it should :-)
Greetings
Alex
