Thanks for replies.
I have now tried the Nouveau driver, and Loch works.
Unfortunately I experience quite a lot of other problems with the nouveau driver. When booting with the nouveau driver I end up with a black screen, I need to use the acpi=off linux boot parameter to not get a black screen, but then I am not able to choose a higher screen resolution. This was the reason I changed to the propietary driver in the first place. This makes the nouveau driver not much of an option unless I can solve this problem, but I guess that is outside the scope of this list.
Anyway, it then seems like my loch-problem is somehow related to the propietary nvidia driver.
Best regards
Bjørn Egil