samba - Nov 2007 - fcntl_lock: lock failed at offset 0 count 1 op 13 type 0 (Resource temporarily unavailable)

Samba 3.0.26a, two different RHEL4 boxes and a Fedora 2 box.

I'm seeing this message whenever I do anything to nmbd with smbcontrol, 
for example smbcontrol reload-config or smbcontrol debug.

[root@fleetwood samba]# smbcontrol nmbd reload-config
params.c:pm_process() - Processing configuration file 
"/etc/samba/smb_all.conf"
Processing section "[homes]"
Processing section "[netlogon]"
Processing section "[profiles]"
Processing section "[print$]"
fcntl_lock: lock failed at offset 0 count 1 op 13 type 0 (Resource 
temporarily unavailable)
Registered MSG_REQ_POOL_USAGE
Registered MSG_REQ_DMALLOC_MARK and LOG_CHANGED

It does not come up for smbd. I have noticed this message in the winbind 
logs an awful lot:

[2007/11/14 11:33:17, 3] libsmb/namequery.c:get_dc_list(1489)
   get_dc_list: preferred server list: ", *"
[2007/11/14 11:33:17, 3] lib/util.c:fcntl_lock(2004)
   fcntl_lock: lock failed at offset 0 count 1 op 13 type 0 (Resource 
temporarily unavailable)

I have quoted the previous line because that always precedes the 
fcntl_lock one.

My users have reported locking up of their XP machines when accessing 
Samba shares since I upgraded to 3.0.26a, so my first point of interest 
was to resolve any error messages. This being one of them.

Any pointers on this gratefully received!

Phil