高手救命啊！！！－＞（重载运算符出错）

头文件：
#include<iostream>
#include<iomanip>
#include<string>

using namespace std;


class newtime24
{
　　public:
newtime24(int h=0, int m =0):hour(0),minute(0)
{
normalizeTime();
}
//一组＋运算符 ++++++++++++++
friend newtime24 operator+(const newtime24& lhs, const newtime24& rhs)
{
return newtime24(lhs.hour+rhs.hour,lhs.minute+rhs.minute);
}
friend newtime24 operator+(const newtime24& lhs,int min)
{

return newtime24(lhs.hour,lhs.minute+min);
}

friend newtime24 operator+(int min, const newtime24& rhs)
{
return newtime24(rhs.hour,min+rhs.minute);
}
// - - - -- -
friend newtime24 operator- (const newtime24& lhs, const newtime24& rhs)
{
　　int currTime = lhs.hour*60 +lhs.minute;
　　int tTime = rhs.hour*60 + rhs.minute;

if(tTime < currTime)
　　　 throw string("time24 duration():argument is an earlier time");
　　else
　　　　return newtime24(0,tTime-currTime);
}

friend bool operator==(const newtime24& lhs, const newtime24& rhs)
{
　　　　return (lhs.hour*60 +lhs.minute)== ( rhs.hour*60 + rhs.minute);
}
//
friend bool operator<(const newtime24& lhs, const newtime24& rhs)
{
　return (lhs.hour*60 +lhs.minute)<( rhs.hour*60 + rhs.minute);
}
// iostream
friend ostream& operator<< (ostream& ostr, const newtime24& t)
{
ostr << setfill('0') << t.hour << ":" << setw(2) << t.minute;
return ostr;
}
friend istream& operator>>(istream& istr, newtime24& t)
{
char setparatChar;
istr >> t.hour >>setparatChar >> t.minute ;
t.normalizeTime();
return istr;
}
// 成员函数+=
newtime24& operator +=(const newtime24& rhs)
{
*this = *this +rhs;
return *this;
}
newtime24& operator +=(int min)
{
*this = *this + min;
return *this;
}

　　　　int getHour() const {return hour;}

　　int getMinute() const {return minute;}


private:

int hour,minute;
void normalizeTime()
{
int extraHours = minute / 60;
minute %= 60;

hour = (hour + extraHours ) % 24 ;
}
};

／／测试的main
#include <iostream>
#include "newtime24.h"

using namespace std;


int main()
{
newtime24 apptTime, totalApptTime;
int apptLength;

int i;

for(i=1;i<=3;i++)
{
cout << "Enter start of appointment and length in minutes: " ;
cin >> apptTime >> apptLength;

cout << "Appointment " << i <<": start: " << apptTime
<< " stop: " << (apptTime + apptLength) << endl;
totalApptTime += apptLength;
}
cout << "Total appointment time: " << totalApptTime << endl;
return 0;
}
编译错误信息：
Compiling...
appt.Cpp
f:\simplycpp\数据结构\newtime24.h(32) : fatal error C1001: INTERNAL COMPILER ERROR
(compiler file 'msc1.cpp', line 1786)
Please choose the Technical Support command on the Visual C++
Help menu, or open the Technical Support help file for more information
Error executing cl.exe.

appt.obj - 1 error(s), 0 warning(s)

好去掉头文件的－号重载，编译成功，但是＋　＋＝　２个重载运算符不起作用！
apptTime + apptLength　＝０？？／／错误
totalApptTime += apptLength　＝＝０？？　／／错误！
但是输出输入>>　　＜＜又行！！
请问什么原因啊？？i