Duda con graficos

Hola que tal te va?? Bueno alla va la pregunta...
Solo queria saber por que cuando ejecuto este código me salen las imagenes cortadas o movidas en pantalla si estan exactamente en las mismas coordenadas, muchas gracias un saludo.
#include<iostream.h>
#include<ctype.h>
#include<dos.h>
#include<graphics.h>
#include<stdio.h>
#include<graphics.h>
#include<stdlib.h>
#include<conio.h>
void espera_retrazo(void);
void main(void)
{
int tirada=0;
int gdriver=DETECT,gmode;
initgraph(&gdriver,&gmode,"");
randomize();
do
{
setactivepage(1);
cleardevice();
setcolor(WHITE);
rectangle(240,160,400,320);
setfillstyle(SOLID_FILL,WHITE);
floodfill(281,241,WHITE);
tirada=(rand()%6)+1;
switch(tirada)
{
case 1:
{
setcolor(BLACK);
circle(320,240,15);
setfillstyle(SOLID_FILL,BLACK);
floodfill(320,240,BLACK);
break;
}
case 2:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(360,200,15);
circle(280,280,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
break;
}
case 3:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(360,200,15);
circle(280,280,15);
circle(320,240,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(320,240,BLACK);
break;
}
case 4:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(360,200,15);
circle(280,280,15);
circle(280,200,15);
circle(360,280,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(280,200,BLACK);
floodfill(360,280,BLACK);
break;
}
case 5:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(320,240,15);
circle(360,200,15);
circle(280,280,15);
circle(280,200,15);
circle(360,280,15);
floodfill(320,240,BLACK);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(280,200,BLACK);
floodfill(360,280,BLACK);
break;
}
case 6:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(280,240,15);
circle(360,240,15);
circle(360,200,15);
circle(280,280,15);
circle(280,200,15);
circle(360,280,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(280,200,BLACK);
floodfill(280,240,BLACK);
floodfill(360,240,BLACK);
floodfill(360,280,BLACK);
break;
}
}
setactivepage(0);
cleardevice();
setcolor(WHITE);
rectangle(240,160,400,320);
setfillstyle(SOLID_FILL,WHITE);
floodfill(281,241,WHITE);
tirada=(rand()%6)+1;
switch(tirada)
{
case 1:
{
setcolor(BLACK);
circle(320,240,15);
setfillstyle(SOLID_FILL,BLACK);
floodfill(320,240,BLACK);
break;
}
case 2:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(360,200,15);
circle(280,280,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
break;
}
case 3:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(360,200,15);
circle(280,280,15);
circle(320,240,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(320,240,BLACK);
break;
}
case 4:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(360,200,15);
circle(280,280,15);
circle(280,200,15);
circle(360,280,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(280,200,BLACK);
floodfill(360,280,BLACK);
break;
}
case 5:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(320,240,15);
circle(360,200,15);
circle(280,280,15);
circle(280,200,15);
circle(360,280,15);
floodfill(320,240,BLACK);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(280,200,BLACK);
floodfill(360,280,BLACK);
break;
}
case 6:
{
setcolor(BLACK);
setfillstyle(SOLID_FILL,BLACK);
circle(280,240,15);
circle(360,240,15);
circle(360,200,15);
circle(280,280,15);
circle(280,200,15);
circle(360,280,15);
floodfill(360,200,BLACK);
floodfill(280,280,BLACK);
floodfill(280,200,BLACK);
floodfill(280,240,BLACK);
floodfill(360,240,BLACK);
floodfill(360,280,BLACK);
break;
}
}
setvisualpage(1);
espera_retrazo();
delay(500);
setvisualpage(0);
espera_retrazo();
delay(500);
}while(!kbhit());
getch();
}
void espera_retrazo(void)
{
while((inportb(0x3DA)) & 8 ==0);
while((inportb(0x3DA)) & 8 !=0);
}