Now that you mention this, just before I turned in my 05 Buick LaCrosse CXS, the same thing happened to me one day. This was when I was still driving it and before I cleaned it up to return it.
The wipers would stop anywhere if I was changing the speed or position i.e. intermittent to low. When this happened, the ONLY position that would work was full speed. Then, after a while it would go back to normal operation. Since the car was right at the end of the lease, I didn't bother to bring it back to the dealer. You know how I feel about that! I think my 300M experiences have jaded me forever with dealer repair shops. I almost shudder when I just go in to have the oil changed!
Maybe this is something GM needs to look into? Short of calling Detroit corporate, since "customer service" will have NO clue what to do with the information, I wonder what would be the best way to bring this to their attention? I would THINK that in this day and age, there is a division at GM that tracks the problems that customers have when a car is in for warranty work?
Maybe GM is already aware of the problem. Then again, there are most likely people HERE who could call it to GM's attention because of their connections if they wanted to do so.
Maybe just reporting it to
http://www.nhtsa.dot.gov would be a good start?
NO word yet on my LTZ! MAYBE today? It left Fairfax, I think and not Orion, on January 9th! How long does it take to get from there to the dealer in RI? They gave an estimated date of arrival as this Wednesday the 23rd! I can't wait!