Keyboard properties changing unexpectedly

I have a problem with my pretty new Dimension 5100, which never occurred to me before. I am using a Swedish keyboard setup (as you may know in Swedish we have a number of different letters such as å, ä, ö etc.)

When I am using Word (I am running on XP) my keyboard properties may suddenly change over to another setup. It happens right in the middle of writing and I have to reboot to get back to the normal setup.

Any ideas anybody?