The 1.6.0 version crashes my Ubuntu on one of my 5850. When I use the kernel on the other card, everything works fine. I now mine with phatk2 on one card and phatk on the other. This combination works.
I think it has something to do with the video output. I have the screen plugged in on the card that i mine with phatk2 with. The other one, that crashes doesn't have a screen or dummy plug.