Its a physics bug.
You should create a capx with only events that produce the error. Especially if what you are working on contains content you purchased from the store.
It may be a physics bug, but it is related to setting the width of the sprite with the physics behavior attached.
Also, the content is created by me. These events were in a template I uploaded to the store ( I have recently updated it to a working version that is awaiting approval)..