Code:
#include <iostream>
#include <string>
#include <cstdlib>
#include <stdlib.h>
#include <windows.h>
#include <stdio.h>
#include <time.h>
using namespace std;

int Wait ( int Seconds );

int main ( void )
{
char scan;
while (scan != 'n')
{
string a("Norton anti virus scanning \n");
string c("7 Hits\n");
string d("Viruses found: 4\n");
string e("Code red Worm\n");
string f("Nimda Virus\n");
string g("Love Bug Virus\n");
string h("Kevlarsmart Worm\n");
string j("Trojans: 3\n");
system("cls");
cout << "scan system? Y or N: ";
cin >> scan;
cout << a;
Wait (5);
cout << c;
Wait(3);
cout << d;
cout << e;
cout << f;
cout << g;
cout << h;
cout << "No files fixed\n";
Wait(2);
cout << j;
cout << "No files fixed\n";
Wait(4);
cout << "Scan again? Y or N: ";
cin >> scan;
    {
    while (scan != 'y' or 'n')
    cout << "Invalid command";
    Wait(2);
    return 0;
    }
}
}
int Wait ( int Seconds )
{
    clock_t endtime = clock() + Seconds * CLOCKS_PER_SEC;
    while ( ( clock() < endtime ) );
    return 0;
}
I can type s at the start and it scans. at the end, however, i get:

Invalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid

Forever and ever.
No matter what i type.
Should i use a goto loop, a while loop, or if, or what?
How can i fix that?

It looks like this at the end:

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Scan again? Y or N: n
Invalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid
Invalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid commandInvalid
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