Bluescreens (out of the blue), new Dell XPS 8300, Win 7 Ultimate ???

I get Bluescreens, really out of the blue, unexpectedly, with a brand new Dell XPS 8300, Windows 7 Ultimate ???
Hardware check, especially memory, is ok.
Dell Support is active, but I do not blame this, at least for now.
All ideas welcome how to avoid this trouble.
Thanks,
Hanns