samba - Jul 2005 - nmbd intermittently delaying responses to name querie s

> My PDC Samba nmbd is intermittently delaying responses to 
> name queries.  As
> an example, i run:
> 
>   nmblookup -U 192.168.75.11 -R "PDC#1C"
> 
> from a member server, and the .11 machine will respond.  
> Repeat this a few
> times, and the .11 machine stops reponding.  After a while 
> (and you keep
> trying, add "-d 10" to the command-line...) the .11 starts 
> responding again.
> Sometimes with what appears to be a queued up set of 
> responses (ie: the
> output of nmblookup shows only 2 requests going to the .11 
> box, but the .11
> box responds 12 times).   If I run a "tcpdump port 137" on 
> the .11 box, I
> can see the requests arriving at the box.

More information:

It seems whenever the nmbd isn't answering, the process appears to be stuck
in a certain mode.

hostname:~# ps -le
F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD
4 S     0 25538 25537  0  69   0 -  1490 wait_f pts/0    00:00:00 nmbd


Does anybody have any idea what might be causing this?