It means your headset (the bearings that the fork turns on) is worn out. It prefers to settle into set positions because the ball bearings are finding little worn out dimples in the bearing surfaces to rest in.
You can go to an LBS and have them install a new headset, but the job will run in the neighborhood of 65$. Considering that this is a significant proportion of the bike's monetary value, you may be better off noticing that many other areas of the bike are also worn out and that its cheaper to just buy a new bike.