closed as off topic by gnat, MichaelT, Bart van Ingen Schenau, GlenH7, Martijn Pieters May 19 at 14:17
Questions on Programmers Stack Exchange are expected to relate to software development within the scope defined in the FAQ. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about closed questions here.
You did not mention whether or not you are coding in a managed environment. For managed environment there is an option named "just my code" that should do the trick.
More information can be found on the MSDN.
I think you might have accidentally hit the F11 key while debugging which allows stepping into the code (of other library packages, unintentionally). Red Gate Software's .NET Reflector also allows stepping into other packages 'they call it a feature of the product'. Try hitting the F10 key for stepping out when you meet a line / code that was adopted from an external library you don't want to get into.
Follow Below Route: