Why can't I debug?

Question

When I was about to debug C++ program in VS2005,the program didn\'t stop at the breakpoints.

The VS said\"No symbols are loaded for any call stack frame. The source

Answer 1

Just to add another possibility not yet covered by MainID:

When debugging, I actually started some program that would call into the classes I wanted to debug (it's some sort of add on). The called program is partly written in unmanaged C++. When I checked "Enable unmanaged code debugging" the error would come up (and subsequently the program crashed) because the program did not have any debug information.