typedef struct MYSTRUCT1
{
   somestuff;
   somestuff;
   somestuff;
} MYSTRUCT1;

typedef struct MYSTRUCT2
{
   MYSTRUCT1* aVariable;
   somestuff;
} MYSTRUCT2;

MYSTRUCT2 hereItGoes;

function MyCoolFunction()
{
   hereItGoes.aVariable = (MYSTRUCT1*)malloc(sizeof(MYSTRUCT)*iNeedItSeveralTimes);
   int index;
   for(index = 0; index <= iNeedItSeveralTimes; index++)
     hereItGoes.aVariable[index] = aValue;  //<-- problematic line of code is here
}

MYSTRUCT2* hereItGoes;   //not sure if your declare of hereItGoes is valid

function MyCoolFunction()
{
   hereItGoes = (MYSTRUCT2*)malloc(sizeof(MYSTRUCT2));  //I always use malloc cause I can never be sure. 
   hereItGoes.aVariable = (MYSTRUCT1*)malloc((int)sizeof(MYSTRUCT)*iNeedItSeveralTimes);   //MAKE SURE the (int) is inside the malloc or it will fail
   //this line may also need to be "hereItGoes->aVariable = ..." but not sure
   int index;
   for(index = 0; index <= iNeedItSeveralTimes; index++)
     (hereItGoes->aVariable)[index] = aValue;  //you have to use the "->" in place of "." when dealing with strunct inside structs
     // and the PLACEMENT of the brackets around "(hereItGoes->aVariable)[index]" is VERY important
}