CIFS mount errors

["Robert S" <robert.spam.me.senseless@gmail.com>]

I have several mounted CIFS shares to a Win XP Pro server.  This
usually functions well for a few days/hours then I get input/output
errors.  When I unmount them and try to reconnect I get:

# mount -a -t cifs
mount error 5 = Input/output error
Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)
mount error 5 = Input/output error
Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)


I get this in my syslog

Aug  7 11:39:38 debian kernel:  CIFS VFS: Send error in SessSetup = -5
Aug  7 11:39:38 debian kernel:  CIFS VFS: cifs_mount failed w/return code = -5
Aug  7 11:39:38 debian kernel:  CIFS VFS: Send error in SessSetup = -5
Aug  7 11:39:39 debian kernel:  CIFS VFS: cifs_mount failed w/return code = -5

I hope somebody can help with this - its a very frustrating problem.
I haven't found a fix anywhere on the net.