Kpeters913, when you start debugging, each project in the solution will be checked to see whether it needs to be rebuilt but unless the dependant files are newer than the targets that check should not actually result in anything being rebuilt. You will see status messages appear in the output window for each project but that does not mean that a rebuild has occurred. If the files are actually being rebuilt then that is a bug.
Cheetalm, your suggestion will prevent the project from ever being built which I would imagine is not what the orginal poster wants.