Error when using constraints

Good morning, 

I have created  a concrete approach slab with rebar  using constraints so that we can modify the roadway width and the rebar can move with the object. 

The issue is when I go in to change the roadway width constraint the program freezes and an error occurs every time. 

Has this error occured for anyone else? 

Attached is a picture of the error that occurs when changing with constraint for roadway width