blitting is the process by which an entire screen worth of graphics is loaded into memory and then "blitted" all at once onto the screen...

so a program might maintain a couple of copies of what should appear on the screen that are different and blit between them... at least this is how graphics libraries in the 90s worked.

In case it helps someone else -

I had seriously distorted graphics, which were fixed by switching to software rendering (as opposed to the hardware T&L options.)

I just want to add something to this, I've had some serious flickering (right at the start without being able to read the menu). Turning off CrossfireX did the trick for me.