help debugging

I'm trying to debug my program can anybody help?

Here's a part of the code

cin >> order;
while(order!=1 && order!=2 && order!=3){
cout << "Invalid input, please input valid input"<< endl;
cin >> order;

When I enter negatives and 0 it works fine, but when I enter letters it goes into an infinite loop of "Invalid input, please input valid input". Any way I can fix this?

>>10
This is the END for you, you gutter-crawling cur!