Software :: Ubuntu 10.4 VB Guest Cannot Write To Shares On 9.10 Host

I just upgraded to the newest VirtualBox, version3.2.4.r62467 and installed Ubuntu 10.4/64 guest on an Ubuntu 9.10/64 host. I installed the guest additions and set 3 shared drives. I can see them in the "machine folders" names, paths and access modes in the "shared folders" dialog. But, when I try to write to them, I always get Permission Denied!

I mounted it as root:
mount -t vboxsf tera /vb/tera
It shows up in mtab:
root@ubu-10:/vb# grep tera /etc/mtab
tera /vb/tera vboxsf rw 0

I can see the listing:
root@ubu-10:/vb# ls /vb/tera
bak Recycled <snip>

But, the permissions are wrong and can not be corrected. Chmod and chown are ignored?!
root@ubu-10:/vb# ll /vb | grep tera
drwxr-xr-x 1 root root 12288 2010-05-04 09:42 tera/
root@ubu-10:/vb# chown brianp /vb/tera
root@ubu-10:/vb# chmod 775 /vb/tera
root@ubu-10:/vb# ll /vb | grep tera
drwxr-xr-x 1 root root 12288 2010-05-04 09:42 tera/

I am running as root:
root@ubu-10:/vb# whoami
root
The VB shared folders dialog, machine folders shows /tera with access Full. /etc/mtab confirms that it is rw

I own it on the host:
brianp@trex:~$ ll / | grep tera
drwxr-xr-x. 16 brianp root 12K 2010-05-04 09:42 tera
Why can't I write to it?