Samba Domain Login

[Finn Blucher]

Okay,
   I'm really starting to run out of ideas here. Any help would really
be handy. I'm looking after a small network, clients are running win2000
SP3 and a Linux Server running samba, doing domain logins. Everything is
working fine apart from two machines (from ten). Probably once a week
one of them will fail to login in after a reboot or log off. If any
user tries to login into the domain it comes up with the error "The
system cannot log you on to the domain because the systems computer
account in its primary domain is missing or the password on 
that account is incorrect." Now the fix for this is simple enough. I log
into the local machine put the workstation back to a workgroup, reboot,
log in and re-add the computer to the domain and every ones happy ( for
a week or so). I've re-imaged the machines from one of the machines on
the network that doesn't exhibit the problem and sure enough, after a
week or so, down she goes. I've physically swapped one of the failing
machines out for a working one and shortly after the "new" machine is
failing again. There is no difference in the software or hardware
between any of the machines on the network, all part of the same roll
out, all on the same image. All of the machines except for one have done
had this problem, but only once, after I put them to workgroup then back
to domain they're happy and have been for six months, it's just these
two machines that keep doing it. The two failing machines are not near
each other but they are occasionally used by the same user. I've got the
logs if that will help people.

Any help really apreciated,
Finn.