I am experiencing a really strange networking problem which I hope someone might be ABLE to help with.

I have a three year old Windows-XP Desktop System (HP Pavilion A145) with Linksys 54G wireless card configured in Ad-Hoc mode, with WEP activated. Other wireless enabled SYSTEMS in the house have been wirelessly connecting to the Internet via the HP's Alcatel Speedtouch USB ADSL connection until recently.

But for the past few weeks I have only been able to connect from a remote system for about one minute before the remote connection stops responding. The Internet still works on the local system. A reboot of the HP and once again the remote systems (tried from three different systems running W-98, W2k and W-Me) can connect again to the Internet for a short time, enough to download one or two pages and then it goes dead.

The remote systems show the wireless connection is still up; IPCONFIG shows the remote computer still to have its assigned IP address (e.g. 192.168.0.32), however a ping back to 192.168.0.1 times out. Pinging 127.0.0.1 is still working. Back on the HP host system, Control Panel/Network Connections shows:

Alcatel Speedtouch Connection - Connected, Shared
Network Bridge - Connected
Wireless Network Connection - Connected, Bridged

All systems are free of viruses and Spyware and have up to date AV and anti-spyware signatures. I have swapped out the HP host's wireless card for a spare one, but the symptoms remain the same. There is a ZoneAlarm firewall active on the local system; XP Firewall is disabled.

This set-up has been working fine for over two years. I am completely stuck as to what to try next. Is it perhaps some kind of accidental interference or Denial of Service from a neighbour (there are SEVERAL other wireless signals in the vicinity)? What else can it be? What can I try? I'd be really pleased to hear any ideas as I am at my wits' end.
Yes, you're right, wireless LANs are prone to interference problems.  Anything from neighbouring LANs to your own microwave/boiler/vacuum cleaner can degrade network performance.  I see you are using internet connection sharing.  In your wireless network you have two main points of failure then: the quality of the radio environment, and the ICS "server" (your HP).

In your situation, the first thing I would do is ditch ICS - for several reasons: the dependence on one PC, the inherent performance degradation, the reliance on a software firewall, etc.  A good solution would be an all-in-one DSL modem/wireless router/firewall.  Those gizmos are very much cheaper now than three years ago.

This immediately takes the ICS server out of the loop, and gives you a much better firewalling system to boot.  If LAN-wide internet access remains as poor as before, you can look to the radio environment for your problem.

To test your wireless LAN quality without changing to a wireless router, you could try the following: set up Windows filesharing, and try moving some large (e.g. 50MB+) files around the network.  See what happens.Thanks, robpomeroy, some good thoughts there.

I was actually planning to switch to a router before this started happening, so I will CONTINUE with this plan, but I had wanted to start with a working system, before making any changes! One other thing I might try, that you just made me think of, is changing channels from 1 to 7 or 15. My setup doesn't do this automatically, but if it is interference, then that might help.

The file share is already set up, but of course doesn't work either, after ping stops working.

Regards,
tbrakeOkay.  Post back with any other problems?Confirm that your hardwares (modem/router/switch) is working fine. Check by replace with a proven working one from a friend.
If the hardware is on 24 hours for 2 years it probably is gone.
My router has just retired recently.I ran into this once with an older netgear wireless router. everything worked sweet for about a year until..... my neighbors got a wireless linksys router. After that I could no longer use my wireless router for more than a few minutes.That may be my problem... :-?