This isn't necessarily a linux problem. But I thought someone here my
know what the technical issue is.
Computer A NT computer
Computer B linux computer

1) After 7 + years, an NT computer on our network has developed a
periodic problem where it just loses network connection. The
connection just stops and we can't ping it and then it will start up
again.

2) The network card was been replaced and port on main building switch
changed.

3) An 8-port switch was added at the drop and another computer
(Computer B) was placed on the switch. Network problem stopped for 2
weeks.

4) Computer B was removed from 8-port switch. Within 14 hours the NT
computer started losing network connectivity.

I tried to find out a number of times what had changed. Answer
'Nothing'. I then was talking to one of the users and they reported
that the whole problem seem to start about 2-3 weeks after a new
version of software was installed. Going from 5.1 to version
5.1.xxxx. I'm not convinced this is the problem, but it's awful
suspicious at this time. I just can't think of anything that this
software could be doing that would cause the problem.
The software uses a PCI board to communicate with a robot and gather
data.
I don't see another ether connection when doing ipconfig.

If I throw out the software issue, what could I be looking for on
this computer that would indicate what the problem is? Is there a
buffer or cache I can or should be monitoring?

If I put Computer B back on the 8-port switch and the problem goes
away, what is that telling me?