No Source Available
Your project does not contain source code for the code that you are trying to view. The usual cause is double-clicking a module that does not have source code in the Call Stack Window or Threads Window. You can continue to debug, but cannot use the source window to set breakpoints and perform other actions at this location. If you need to set a breakpoint, use the Disassembly Window instead.
In the Solution Property Pages, you can change the directories where the debugger looks for sources files and tell the debugger to ignore selected source files. See Debug Source Files, Common Properties, Solution Property Pages Dialog Box.