PIC shutting down

                SetChanADC( ADC_CH0 );
		ConvertADC(); 			//ADC conversion
		while( BusyADC() ); 		
  		result = ReadADC();
  		
  		if(result > max) max = result;
  		
  		itoa(result,output);		//Convert ADC result to string
  		reading1(output, 5);

  		//This is the section that causes problems
  		itoa(max,output);		//Converts max to string
  		reading1(output, 14);

void reading1(char* reading1, char pos){ 	
	int i,j = 0;
	char temp[6];
	
	for(i = strlen(reading1);i >= 0;i--){  //Copy reading1 into a temp array
		temp[i] = reading1[i];
	}
	
	for(i = 0;i <= 4-strlen(temp);i++){   //Add spaces
		reading1[i] = 32;
	}
	
	for(i = 4-strlen(temp); i <= 5; i++){ //Copy temp back into reading1
		reading1[i] = temp[j];
		j++;
	}
	
	str_decimal(reading1,1);                 //Format number with 1 dec place
	LCD_pos(1,pos);                           //set cursor position
	LCD_text(reading1);                      //Output to LCD
}