samba - May 2006 - Kernel Panic saving a file via samba to an overquota account

My samba server panics (and crashes) periodically (even under no load) and
"current process" usually indicates "smbd".

It seems to happen when saving changes on a file of an overquota account share
(from a nfs mounted file system).
When samba is sharing only local file systems it doesn't seem to happen (at
least never happened :-)
Does anybody had the same problem and found a way to fix it? 

The server OS is freebsd 6.1 and samba 3.22.

Thanks for any help!

Emidio