Hope anyone can help me out, as I'm wrestling with this for days already.

While everything worked fine before, all of a sudden the internet cannot be accessed from one machine in my network anymore. The silly thing is that sometimes (seldom) I can access the internet right after rebooting the machine, but that will last only a second or 10, then no access is possible anymore. The status of the lan indicates connected however.

Situation:
* 8 way switch, encore ENH908-NWY.
* static ip addresses
* other machine works perfect with exactly the same settings (except, of course, the ip address which is one higher)
* VIA Rhine II Fast Ethernet Adapter, on board

What I tried without result:
* switched cables
* switched ports on switch
* bypassed switch by connectig machine directly to modem.
* checked device manager - nothing seems wrong with the ethernet adapter, at least this is not indicated
* virus scan gave no results
* ad aware scan no results
* did ipconfig /all on both machines to compare results, nothing seems wrong
* ran winsockxpfix.exe
* changed from static ip to "automatically obtain", and vice versa
* reinstall the ethernet device

The only moment the internet works for a few seconds, is after booting first thing in the morning. Could it be that the ethernetcard is not functioning properly after temperatures rise during the day after using the computer? Anyone experience with this on board card type?

I don't see where you tried another NIC.

Life's more painless for the brainless.

All the signs that your ISP is only giving you one ip address and you were actually taking one from them you hadn't paid for.

They figured it out.

This is why everyone puts in a router not a switch. A router uses one ip and nats it to many lan ips with the additonal feature of protecting you from hackers/port trojans on the internet.

Imagine the power if you knew how to internet search

Thanks for your answers :-)

@Jennifer: No, it's a notebook with an onboard NIC. it's difficult to put another one in.

Thanks for your answers :-)

@wanderer: you think so? I wondered about that. But that would not explain the fact that, when I bypass the switch completely and plug the machine directly in to the cable modem directly it still does not function - is it?

Also: that wouldn't explain how I can connect with the other machine as the only machine in the network, while I can't with this machine as the only one in the network.

Besides that, I believe the modem also has built in router function, but maybe I should check this again.

I would swap out the NIC with one of your other working PC. If that doesn't fix the issue then what Wanderer commented on is more likely the problem. Your internal IP should be different from your external...

Actually it explains it perfectly.

When a isp assigned you a ip it logs your nic cards mac address. This is why the one you registered with works and the one that doesn't does not work.

Get yourself a soho router and be done with it.

Imagine the power if you knew how to internet search

I just got news from the shop where I bought the computer. It turned out that the onboard network card was burned.
So that's the ultimate answer to the mystery.