audio buzz

Hello,
I have buyed a new pc with audio integrated on the motherboard.
In Windows XP, if I set the SoundMax Panel Control mixer settings
to capture from line in, or cd player, or mic in, I hear a buzz in
synchro with mouse movements (if I set stereo mixing, no - but how
to record?).
It is like scratching with the mouse.
Can this behavior considered normal or I should go to my vendor and
say to
change my motherboard?
Please do not reply me that this is not hardware to do recordings, I
know,
the only things I register are radio shows that my old pc handle in a
good way (however, separated audio card). Ah, my motherboard is
an Asus M2N.
Thanks a lot and excuse me to waste your time,
tano