I dont understand what the great deal is about people thinking racist thoughts.
EVERYONE does it, I dont care how PC you get. Its one of our biologically hardcoded survival tactics, to be wary of people outside your "tribe" (obviously referring to races here). Its absolutely normal to be afraid / threatened by people who are 'different', and unfortunately, this does include race.
I'd say the only difference between a racist and everyone else, is that a racist will not change his mind even if he finds an individual who goes against the stereotype of his race, incites some kind of violence or hatred against other races, or really discriminates them in things like work.