@TURBODREAM
many of us have had better luck with our software, with a full reinstall of windows....
but you could just try a complete uninstall of your GFX drivers, and then a new reinstall...
and if that doesnt work;
shutdown computer
open case
remove 2nd GFX card (and sli cable)
boot up
shut down
reinstall 2nd GFX card (and sli cable)
reinstall drivers