"make: permission denied" error when doing "make installworld"

[Mike Tibor]

(if this question is more appropriate for freebsd-stable, let me know)

I'm trying update one of my servers, and can't get past a "make:
permission denied" error when doing a "make instalworld" as root in single
user mode.  My sequence was this:

cvsup
make buildworld
make buildkernel
make installkernel
shutdown now   (go to single user mode)
make installworld

I'm I missing something?  I've run into this once before on another
server, and just did a binary upgrade to get around it.  The thing is,
I've successfully upgraded along the -STABLE tree via this method
countless times.

/ is mounted rw, and /usr/bin/make is executable.

If anyone has any idea what I might be doing wrong, I'd greatly appreciate
it if you could point me in the right direction.

Thanks,
Mike