samba - Sep 2003 - Freebsd lockup smb_maperror:Unmapped error 1:158

Almost everyday my FreeBsd 4.8 machine with Samba from ports locks up
with

 smb_maperror:Unmapped error 1:158
 /kernel: :158
 last message repeated 758 times


 Machine has to be reset to get it back up and running. Any ideas?

 Thanks,
                      Patrick