2001 Chevrolet Venture "Power" sliding door problem!

Hello, everyone!! I own a 2001 Chevrolet Venture which has dual "power" sliding doors. Just recently, the driver’s side started acting up. When I go to close the power door it will close to about 3/4 of the way, then for no reason, reverse direction back to the open position. It will do this about 90% of the time. Any advice would be truly appreciated. I thank you for all, in advance, for any responses. Thank you.