为什么这个程序会崩溃:在 DLL 之间传递 std::string

I have some trouble figuring out why the following crashes (MSVC9):

//// the following compiles to A.dll with release runtime linked dynamically
//A.h
class A {
  __declspec(dllexport) std::string getString();
};
//A.cpp
#include "A.h"
std::string A::getString() {
   return "I am a string.";
}

//// the following compiles to main.exe with debug runtime linked dynamically
#include "A.h"
int main() {
   A a;
   std::string s = a.getString();
   return 0;
} // crash on exit

显然 (?) 这是由于可执行文件和 DLL 的内存模型不同.会不会是A::getString() 返回的字符串在A.dll 中分配，在main.exe 中释放?