[vbox-dev] Why do I get 'Protocol error' when I try to access the shared folder?

[Yuri]

I run Ununtu (32-bit) guest on FreeBSD (32-bit).

Shared folder is defined in FreeBSD host with the name 'vbox', it mounts 
ok. But 'sudo ls /this/mounted/folder' says:
cannot open directory: Protocol error

How to fix this?

Yuri