Sam, the player uses the path of the pits (the tracks) to control the movement (tracking) of the laser pickup. If it can't see the signal, it can't track either. Too sensitive? That's a subjective term.
The fact that cleaning works says volumes about the need to keep discs clean. The player may need calibrating. Take it to a repair place with a 'dirty' disc. (Warranty?)
Larry
www.fineelectricco.com