1. Hydraulic or Electric slide?
2. Since about 2006 or 2007, ALL slides must have the wall button pushed continuously to keep the room moving. That means something(controller or the wall button assbly) activated the mechanism continuously for a full extension. From your description, I will bet it is Electric and not hydraulic since the room operated in reverse of the wall button
3. CONTAC WINNEBAGO FIRST THING MONDAY WITH YOUR UNIT NUMBER. They need to know this happened as it is a dangerous thing.
4. If electric, depending on which system Winne used 10 years ago, I would bet on the Slide control board is defective or has had water intrusion(corrosion) that caused this. You need to involve Winne and a Winne Service Center in this, NOT rely on a RV Forum for an answer. Doug