Applications cannot access internet

Sorry for the long list but I wanted to avoid "to and fro"

1. three computers are on a LAN thru a DLink DI640 router via ethernet
2. All computers on the LAN can access all shared resources
3. All computers can ping successfully on each other
4. All computers which I have allowed internet access can ping successfully on google.ca
5. #1 computer can access the internet with applications:
Firefox3.0.4, IExpl7.0.5730.11, Outlook Exp6.00.2900.5512
6. #2 computer has been blocked from internet access by me in the
router
7. #3 computer cannot access the internet with those same applications
8. #3 OS is WinXP Home
9. #3 Free ZoneAlarm firewall and AVAST antivirus are installed
10. #3 AVAST automatic update gives message "can't update"
11. #3 disabling firewall & antivirus has no effect
12. #3 Firefox with www.google.ca address eventually gives message "Network Timeout"
13. #3 has two Network Interface Cards and I have tried both
14. #3 clicking on MyNetworkPlaces > View Network Connections shows three categories: "Broadband", "Internet Gateway" & "LAN or
High-Speed Internet"
15. #3 clicking on Internet Gateway > Internet Connection shows packets sent & received under Internet Gateway are static while under My
Computer are continually increasing
16. #3 clicking on Broadband > Sympatico shows "Disconnected"
(before the Router was installed, #3 was connected by ethernet to the modem with ISP [Sympatico] supplied the software)
17. #3 clicking on Sympatico opens a window "Connect Sympatico"
with User name already entered & Password "click to change"
18. #3 clicking on Properties > Networking shows:
Type of connection - PPPoE
TCP/IP and QoS Packet Scheduler are ticked
19. #3 clicking on Connect opens a window "Connecting Sympatico - connecting thru WAN Miniport (PPPoE)" - eventually gives error 678
"Remote computer did not respond..."
20. #3 physically connecting #3 to the modem (via ethernet cable) instead
of the router and again clicking on Sympatico shows "verifying Name &
password" and then shows "connected to Sympatico"
21. #3 Firefox can now connect to Google.com, IExpl & OutlookExp can
also connect
22. #3 clicking on MyNetworkPlaces > View Network Connections now shows only Broadband and High-Speed Internet - Internet Gateway is
gone
23. #3 If I disconnect from Sympatico - click back to MyNetworkPlaces & click forward again to ViewNetworkConnections - Internet Gateway is
still gone
24. #3 when this problem first appeared I noticed some kind of message about IP conflict - no other computers were powered up at the time.
25. #3 I did a System Restore to a date before this problem appeared without any improvement

Are you saying that "Internet Gateway" is not working? (correct me if I am wrong)

BiGMaCHiNe

I just meant that the heading "Internet Gateway" had vanished from that window.

The problem has since been corrected. I suspect the Restore did it.

Although I had rebooted yesterday after the Restore, I opened a Limited account rather than the Admin account. When I booted up and opened the Admin account today I got a message that the Restore was complete and everything now works.

The problem seems to be catching.

I have exactly the same problem now on computer #1 (Win 2000) but #3 has been OK since my last post.

I tried a registry restore on #1 which had no effect. There doesn't seem to be much choice with Win 2000 restore.

Any suggestions?

Hello,
Internet gateway problem causes lot of difference what we understood than in the existence but I will suggest you the following link,There's a good set of tips here:
http://practicallynetworked.com/sharing/ics/ics.htm

I'm sure I looked at it a few weeks ago and saw advice on the internet gateway icon but I couldn't quickly find it this time. Maybe if you have a good scout around you might find what you need.