Users losing connection to network...

For the past few days, we have been having a problem where users are losing connection to network resources, as often as every 15 minutes on some computer and sometimes only once or twice a day on others. It is consistantly the same PCs that stay up for longer periods and conistant to those which keep going down every 15 minutes or so.

When a computer is in this state, they are unable to ping other computers, cannot be pinged by other computers, and are unable to access network resources (namely their mapped drives).

If we do an IPCONFIG /release then IPCONFIG /renew, they can be pinged and once again access all network resources. We are using a domain and managing users in Active Directory.

This problem started happening on Friday morning last week. I did rollback some patches I had done to the server after this began happening, but that didn't seem to help. No other major changes were made to the network.

All our computers come into one of two switches that are linked together. Our one server (Windows 2000) is also connected to this setup. I have swapped out both switches and this has not solved the problem. None of these switches are managed.

I recently added a Cisco switch that was a backup for one of our offsite systems. I added two computers on this switch (which is linked to the other two). Neither had problems for many hours. Then I added a third user and all three began having problems. So I removed this third users, but the two remaining are still having issues.

When you ping a computer from the Cisco router, you always get a reply. This seems to "wake up" computers that previously weren't working and they suddenly regain asscess to network drives and can ping/be pinged.

Does anyone have any ideas? I have been working on this for the past three days and am running pretty dry on things to try. I have tried static IPs, which result in the same problem, and it does not seem to matter which switch the users or server is on. I have ran virus scans and Adaware on all PCs and didn't find anything. I have checked for updates on a few and updated network drivers, but that hasn't helped either.

I am thinking there could be something wrong with one of the user's computers that is affect the network, but none of the lights on the switches appear to indicate anything out of the ordinary.

By the way, most of our computers are Windows XP Pro and there are a few 98s. Both seem to experience the same problem.<P ID="edit"><FONT SIZE=-1><EM>Edited by kriswd40 on 08/24/05 05:09 PM.</EM></FONT></P>