Which version(s) of Windows are running on the computers, particularly the one that doesn't work.  Have you tried unitinstalling and reinstalling the network adapter?

Steve

Yes, we've reinstalled the drivers twice.  Both computers on the network are running Win XP Home Ed.  (Sorry, I forgot to mention this in the previous message.)

Try resetting the TCP/IP stack using the information at the following site:

http://support.microsoft.com/default.aspx?scid=kb;en-us;Q299357

Steve

Reseting the stack had no effect on the problem.

Are the link lights on the network card and the port to which it is plugged in on the order lit up?  Are you sure the cable is good (try switching cables)?  Can you ping the network card (go to a command prompt and type ping 127.0.0.1 then hit the Enter key)?

Steve

Have you tried connecting directly to the dsl modem?

Steve

The link lights on the switch and on the NIC are lit and we have swapped cables and there's no problem there.  Pinging 127.0.0.1 or the machine's self-assigned private IP address results in four successfully delivered packets (with 0% loss).  However, pinging the switch or the other computer on the network results in "Destination host unreachable."

Initially, the problem computer was connected directly to the DSL modem, and that worked for about three days.  Then, after booting up one day, this problem started.  We had just received the router/switch and networking equipment, so we connected both computers to the router/switch.  The exact same problem has persisted with the router/switch.

The last thing I can suggest is to download and run lspfix from the following site:

http://www.cexx.org/lspfix.htm

If this doesn't fix the problem, then all I can suggest is to try a different network card.  You seem to have eliminated the network card as being the problem, but the only way to be sure is to try a different network card.  Otherwise, you have eliminated the cables and router as being the problem, and resetting the TCP/IP stack and running lspfix should have corrected any software problems.  Thus, I am at a loss as to explain this.

Steve

Still no success, even with a different NIC.  Thanks for your help, though.

I'm experiencing a very similar problem.
If I do an IPCONFIG /RENEW the system waits, thinks, and then replies that it cannot find the DHCP server.

I've been banging my head against this for a few days.
Have you had any luck since your last post?

Yes, I finally discovered the problem was due to a firewall which was supposedly disabled.  If all else fails, try uninstalling just about everything that's not necessary.  That's how I discovered the firewall problem.

Was it a hardware firewall, like a Linksys or SMC router?
Was it 3rd party software or the native Windows firewall (ICS)?

I've found a workaround to my problem.  It was the auto-negotiate of the line speed.  As soon as I put a 3rd party NIC in that had a firmware setting of 10Mbs the problem went away.  As soon as I went to auto-negotiate the problem recurred again.  Happened on both the onboard and 3rd party NICs.

Thing is, I have 5 other PCs on the network and they ALL auto-negotiate their line speeds.  It's only the Dell that's the problem. 

But hey, it works for now....

It was a 3rd party software firewall.