VS2003 has a confusion when debuging, if you open two files with same filename in VS or the same name cpp file you open is not the one your project including. when this situation happen, you can set breakpoint in the confused file, and debuging just as the file is the right cpp file in your project. so you can see the right logic process of sourse code, but never have the right result you expected.
For example, you have create a new project from a old one, you need to refer the old sourse code, so you also open the old sourse file in you new project. now you need to add a variable to the new cpp file, but you add to old one for careless. and you continue to debug the project, but cann't get the right result, so you set some breakpoints in the old cpp file(you think it's new one), and see the right logic process. now you maybe go into a confusion.