Well, for one thing, the warning you got after the hardware scan-that was a warning that your graphics card doesn't meet the requirements of the game. The thing is, the game can run with that graphics card, it just comes up with that warning because it is newer than the versions of the graphics cards that were released as of K2's release, so no worries there.
As for the flickering screen, I have no idea. It has never happened to me before. Try tuning down the Resolution and maybe turn V-Sync on.
Hope this helped