Memory overflow in atmega32

Currently, I am implementing a stop watch using atmega32 and six 7-segment.

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

unsigned char sec1,sec2,min1,min2,hours1,hours2;
unsigned char finished_flag = 0;

int main(){
    DDRC |= 0x0F;                       //PC0 - PC3 ARE OUTPUT
    DDRA |= 0x3F;                       //PA0 - PA5 ARE OUTPUT
    DDRD &= ~((1<<PD2) | (1<<PD3));     // PD2 , PD3 ARE INPUT
    DDRB &= ~(1<<PB2);                  // PB2 IS INPUT

    //ACTIVATING THE INTERNAL PULL-UP FOR PD2 AND PB2
    PORTD |= 1<<PD2;
    PORTB |= 1<<PB2;
    PORTC &= (0xF0);  //ZERO IS THE INITIAL VALUE FOR THE SIX 7-SEGMENTS.

    SREG |= 1<<7;
    timer1();
    interrupt_int0();
    interrupt_int1();
    interrupt_int2();

    for(;;){
        if(finished_flag){
            TCCR1A = 0;
            TCCR1B = 0;
            sec1 = 9, sec2 = 9, min1 = 9, min2 = 9; hours1 = 9, hours2 = 9;
        }
        display_six_7_segment();
    }

}

then when I run the program on proteus, it says:

"PC=0x1976. [AVR MEMORY] Writing to memory location 0x08BE outside of memory size 0x0860. [U1]"

and it resets my program because it returns the address to the org 0x0000 as showed below:

"PC=0x0000. [AVR CPU] RETI address = 0x0000 [U1]".

I need to know how to reduce the usage of the memory because I only use 7 global variables (6 for each 7-segment and finished_flag variable) and the rest of the code includes ISRs for the external interrupts and timer interrupts.

SOLVED!!!

The problem was in the code of display_six_7_segment(); function.

this is the code before editing:

void display_six_7_segment(){
    PORTA = (1<<PA5) | (PORTA & 0xC0);
    PORTC = (sec1 & 0x0F) | (PORTC & 0xF0);
    _delay_us(2);

    PORTA = (1<<PA4) | (PORTA & 0xC0);
    PORTC = (sec2 & 0x0F) | (PORTC & 0xF0);
    _delay_us(2);

    PORTA = (1<<PA3) | (PORTA & 0xC0);
    PORTC = (min1 & 0x0F) | (PORTC & 0xF0);
    _delay_us(2);

    PORTA = (1<<PA2) | (PORTA & 0xC0);
    PORTC = (min2 & 0x0F) | (PORTC & 0xF0);
    _delay_us(2);

    PORTA = (1<<PA1) | (PORTA & 0xC0);
    PORTC = (hours1 & 0x0F) | (PORTC & 0xF0);
    _delay_us(2);

    PORTA = (1<<PA0) | (PORTA & 0xC0);
    PORTC = (hours2 & 0x0F) | (PORTC & 0xF0);
    _delay_us(2);
}

what I did is just replacing _delay_us(2); with _delay_ms(2);, and then the project worked finely without resetting or errors.

But actually I don't understand what is the problem with _delay_us(2); I know it's very short time but that is what we want to display the six 7-segment at the same time.