Tye believes its a problem with the stdlib call atof() and I tend to agree (the same version of Perl produce different results on different OS's).

From my Linux box with glibc 2.1.3 (that caused the strange float point results with Perl):

nicholas@neko/3:(pts-0.neko) ~/tmp > cat test.c
#include <stdlib.h>

int main(void) {
        printf("%f\n",atof("0x9"));
}
nicholas@neko/3:(pts-0.neko) ~/tmp > cc test.c -o test ; ./test
1.125000
[download]

nicholas@peacock2/5 ~ > cat >test.c
#include <stdlib.h>

int main(void) {
        printf("%f\n",atof("0x9"));
}
nicholas@peacock2/5 ~ > cc test.c -o test; ./test
0.000000
[download]