Running VirtualBox VM host on ReadyNAS Pro

Hello,

I was a happy user on VMware server 2 on top on my readynas ultra 2+ but since I upgraded to the last releases, I have not been able to make it work again. I know, I should have waited for other folks to confirm it would still work...
This is really a pain because I was running a SSL VPn appliance and since I have no longer remote access to my network :cry:

So I decided to migrate to Virtual box and no joy I can not make it work.
I have followed the instructions on this forum but still not working.
I've got the following

 /usr/bin/VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-4.1.0-73009.vbox-extpack
/opt/VirtualBox/VBoxManage: error while loading shared libraries: libcrypt.so.1: cannot open shared object file: No such file or directory

The library is already on the nas:

 find -name  libcrypt.so.1
./lib/libcrypt.so.1

so I tried to link it but still no joy

 ln -s libcrypto.so.1 /lib/libcrypto.so.1
 ldconfig
/usr/bin/VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-4.1.0-73009.vbox-extpack
/opt/VirtualBox/VBoxManage: error while loading shared libraries: libcrypt.so.1: cannot open shared object file: No such file or directory

openssl is the latest version on my nas

 sudo apt-get install openssl
Reading package lists... Done
Building dependency tree... Done
openssl is already the newest version.
0 upgraded, 0 newly installed, 0 to remove

any ideas?