Ok, when I used that code I got an odd error:
request for member `sections'' in something not a structure or union.

So I changed ManifestSection to:

void ManifestSection(struct Section **s, unsigned int x, unsigned int y)
{
struct Section *temp=(struct Section *)malloc(sizeof(struct Section));
temp->grid=(unsigned long int **)malloc(PTRSIZE*10000);
temp->x=x;
temp->y=y;
*s=temp;
}

all things seem to be working without seg faults, but is there a better way to do this without a temporary variable. My attempts at typecasting seemed to fail. Thanks in advance.