Growing up, I was raised with the idea that everybody was equal, and not to discriminate on the basis of the color of somebody's skin. I had many friends from many different ethnic backgrounds, and I can pretty safely say that I really did believe all that.
Since entering the adult world, I've felt a strong bias growing inside of me, from personal experience. Most of the african-american people I've interacted with, starting from college, either screwed me over or tried to screw me over, starting with my roommate in college (didn't pay rent for five months, lease situation meant that either I paid it or I got screwed, and left me stuck with a $1000 long distance phone bill) and just going progressively downhill from there.
Now, most of my interaction with black people has been with people from the lower rungs of the socioeconomic ladder. I haven't had to deal with that many white people from the same group, and those that I have dealt with have been just as willing to try and screw me over. In general, the black people I've met who are doing okay financially are pretty decent people, with one exception - but I considered her an outlier and not statistically significant.
I know that my subconscious reaction to black people is instinctively not to trust them. This saddens me because I know that the real key indicator is economic class, not racial status.