Network Problem in XP

[rolfea]

I've been experiencing a network problem with some XP machines which I have never seen before, seem to be a pain to fix.

The computer looks, and seems to be connected to the network absolutely fine. It has the correct proxy information, it gains a valid IP address with the correct subnet mask and is using the correct gateway.

However, the computer can't connect to the internet or any internal servers. This includes mail servers and file servers.

The weird thing is, I CAN ping Google and I CAN ping all our servers by both name and IP Address.

A tracert to Google shows the predicted results.

We're using Dell Optiplex machines with many different generations and models, but it seems to affecting different models, not just one kind of model. All of the machines are running XP with SP3.

I've tried updating network drivers and updating the BIOS, both of which were unsuccessful. I released the IP address and renewed it, and flushed the DNS; again both unsuccessful in fixing the problem.

One PC was fixed by re-imaging it, so I'm convinced it's not a hardware problem and inside XP. It's happened to a couple, and if it keeps happening I don't want to end up re-imaging the whole school.

Has anyone encountered this before or able to help with any more troubleshooting tips?

[kili]

IP CONFLICT?

[CHR1S]

I had this happen on a new server just this week while downloading and installing new updates. It fixed the issue itself after a restart so didn't look into it any further, sorry its not much help to you.

[rolfea]

IP CONFLICT?

The dialog box should appear saying about an IP conflict, but also I released and renewed the IP address which should resolve a conflict

I had this happen on a new server just this week while downloading and installing new updates. It fixed the issue itself after a restart so didn't look into it any further, sorry its not much help to you.

Thanks for your reply, like all good technicians I did try a reboot.

[BatchFile]

I don't suppose they're all connected to the same switch are they? dodgey switch?

Edit: but then that wouldn't explain why a reimage fixed it....

[BatchFile]

Better suggestion: NIC Driver?

How about trying shoving another network card, usb wireless or whatever in one and see if that works correctly??

[CHR1S]

Thanks for your reply, like all good technicians I did try a reboot.

Do you run a software firewall? Could be random port blocking?

[ajs]

One one of the affected machines have you tried resetting the IP stack just in case something has gone wrong?

netsh int ip reset (I think)

(I doubt it would fix it since you can ping and get other outside connectivity but it won't hurt).

[kili]

A release and renew will not always cure an IP conflict, if the other machine is switched off at the time, But if your using a DHCP server IP probably wont be the problem, sorry just throwing ideas in the pot

[rolfea]

Better suggestion: NIC Driver?

How about trying shoving another network card, usb wireless or whatever in one and see if that works correctly??

Thanks for this suggestion, I'll hunt down an external NIC and try that.

Do you run a software firewall? Could be random port blocking?

According to the network manager, no Firewall has been enabled or configured for the machines. It's done through our ISA Server.

[CHR1S]

can you access your servers via IP instead of name?

[zippo]

Its probably one of two things

(1) Firewall as already stated
(2) Conflicker

It is very common when installing clean PC's for them to get infected the moment they get connected to a network. It just takes one infected machine on your system and - wham ... new machine screwed.

[RobMongoose]

Possibley a rogue DHCP server. An example could be someone trying to join a wireless router to the network to try and use it as an access point.

[rolfea]

The problem ended up being Sophos Firewall.. thanks for all your replies.

After a Sophos update, any newly imaged machines also recieved firewall settings which were never set up by the network manager.

Thanks for your time, hope you don't feel like I've wasted it.