That doesn't really paint a clear picture of what's going on. Can you be more specific, and give examples of when this happens? What do you mean by 'unlocks'? Is the column locking up solid as if the key was pulled out, or are we talking about the tilt steering wheel adjustment?
I would assume how the OP described it, he is having problems with the Tilt. Meaning when he tilts the column down and it locks down to drive, his is not holding and randomly popping up as if you are hitting the tilt to raise the wheel/column up.