I think I found a bug in gcc-4.2
int i, j;
printf("%d %d\n", j, (void *)(j));
This looks like a strict-aliasing issue to me; you're casting from an int to a void*, which is undefined. Did you get any warnings? (Did you compile with warnings enabled? -Wstrict-aliasing?) Investigate the -f[no]strict-aliasing options.
Regards, Phil.