Try:
umount /programs0
ls /programs0

and you will probably see preinit.d
So, after having done this,

rw
cd /programs0
mv preinit.d /etc/
cd /
./mkprgpt

This worked. Thanks.

However, now every time I use the Hijack/CharcoalGray XML web interface to set RW and RO, the player segfaults like crazy in an infintite loop (as described earlier in this thread).