Most interesting thing is that I also had a similar problem, I have a
client with a Samba server and about 500Gb of harddrive space.
The Samba server maintains a large number of locks on files due to
employees not closing the software they using before going home, it is
backed up over NFS to external drives every evening.
About 50% of the backups hang in a D state while trying to access files,
these D states last indefinitly even when locks are dropped on the Samba
server.
-Nigel