[Samba] "the specified network name no longer exists"

[Sam Ami]

hi all

i'm experiencing some really funny behavior on our samba server (CentOS5,
Samba Version 3.0.25b-1.el5_1.4)
from time to time, our xp/2000 users (our workstations are xp/2000 based)
are reporting that while they try to copy a file from one location of the
file server to another, they are presented with the the error....

"the specified network name no longer exists"

if they "retry" the copy succeeds.

background
samba is hosted in an 3 host, ESX 3i cluster.