We use windows 2000 server as SQL 2000 DB server.
IIS, FTP, SMTP are disbaled on the server.
The problem is that every 20 min or so the server cannot be seen by other machines on another subnet (same subnet can see it all the time). We cannot ping, cannot remore connect, cannot see port 1433 (which is what we really need to see.
We remove the firewall so that cannot be the problem. We installed a new NIC (3com) updaed drivers, so that is not the problem either.
We only use this machine as SQL server listening on port 1433.
the web servers stops seeing it until we reboot or the machine decided to start answering again.
We do not have to reboot... if we wait long enough (10 min or so) it will start answering again.
The ISP does not see any special activity on the ports leading to our machine.
All windows updares were applied, no viruses (checked with latest Norton and housecall), Spybot check comes clean too...