It's not that simple. The formatting call is deep inside a "general purpose" routine that renders a Silverlight drawing using graphics primitives and it has a feature to construct strings out of pieces of other strings, controlled by an XML config file. I guess I outsmarted myself by creating this general routine, as it works nicely, but I admit blame for not thinking of the case where the config input contains braces.
So in a sense user input is killing it, but user input from a config file. In future I will pause and think at each string.Format I code to be sure that there is no "brace crash" danger. Greg
