The steering sensor can be a real problem after an alignment if the servicemen is careless, not something that usually goes bad? Was there an alignment done recently?
This makes sence now with your previous post about the brakes coming on while going down the freeway, the sensor falsley read that your car was in a skid and applied the brakes to straighten it out.....tricky stuff

Actually i just had the tires balanced and rotated but no alignment. So i guess your telling me to make sure of who I take it to when it does need to be aligned?

The concern is if they have to replace something during the alignment (ie rod end) and let the steering flop around, it can affect the mechanical limit of the sensor. Also the service bulletin suggests re calibrating the steering sensor after most front end work. I would go to cert. gm mechanic for any front end work as there are too many 'little' things that could go wrong.
Rotating tires or brake work would leave the steering system in place so there should be no real concern.