What the???? Is there a Doctor in the house? Help

[vizion communication]

Ok  do not know what is causing this problem and would
appreciate some help in tracking down the cause.

FreeBSD 4.7

System runs fine for maybe a week and then all networking
stops - without warning. I do not know anyway of  persuading
it to resume networking without rebooting.

Does anyone have some useful suggestions on how to diagnose
the cause?

David