Here's the situation:

The network I keep being dragged out to service (I'm sorry, I'm a programmer, I'm a sysadmin, but making housecalls because they borked their network really stretches my job description) is a bunch of laptops talking via 802.11 to a D-link DI-624 (I think) router hooked to a DirecWay box. There's also a wired Netgear print server hanging off an old LaserJet 5P because they can't be bothered to buy a real network printer.

One laptop (A Toshiba Pentium-M running XP Pro I think) works fine.

Another laptop (some Dell Core 1 Duo laptop running XP MCE, and at least the majority of the Norton suite) has this bizarre issue:

It has two user accounts available. Start from a fresh boot:

If you log into account A, outgoing mail works fine. You can telnet into the outgoing mail server's port 25, you can send mail.

If you log into account B, you generally can't send mail, and you can't telnet to the server's port 25.

If you log into A, log out, then back into A, you lose the mail-sending ability.

If you log into A, then out, then into B, then out, then into A, sending mail doesn't work as B, or as the second time you're A.

Generally, once you lose port 25, you don't get it back without rebooting.

I tried the obvious steps: try using the ISP's SMTP server instead of the company domain's (no-go -- telnet servername.com 25 doesn't work to either server reliably, let alone Outlook sending), tried power-cycling the router and direcway box.... nothing fixes it permanently; only the "Log in as A" procedure gives temporary relief. I even checked the firewall options, but nothing was blocking 25.

My conclusion is *something* is running in the startup of the account B which blocks down outgoing connections to a server's port 25. But then why does the "log in as A, log out, then back in" fail? It must be something that's run on logout on account A too?!

The only obviously odd launch-at-startup app I saw was an online backup provider's system tray icon, which always reported "backup exceptions" The icon looks like the logo for Remote Backup : Online Backup & Remote Backup Software, but of course, they aren't a service provider themselves, and all I can find remotely related to that and port 25 is support FAQs notifying you that certain error messages are related to IT being unable to access port 25 to send status mails.

However, a third laptop (an IBM A21 series sitting in a dock station), they don't use anymore, but it seemed to have the same "cannot telnet to port 25" behaviour; however, I didn't test it extensively so maybe it was an intermittent problem, or just the network card not set right, or if it would work on another account...

It's possible that both the "bum" machines were running the same problematic app, however.

Also, is it unusual to see ping not working for *some* sites you know accept it? From that network-from-hell, you can reliably ping yahoo, but often other sites cannot be pinged (like their corporate site-- which I know can be pinged-- and sometimes not even Google! The pings just time out IIRC)

They claimed it worked until they rearranged their network, which consisted of putting their business-specific application somewhere where it could be accessed on the network, and somehow removing the Thinkpad from play. I expect there was more to it than that.)

I wish I could just wipe the damn machines and try to set them up one step at a time until we found out what was breaking, but they need them for day-to-day business.

Any more suggestions I can lob at them-- all I've been able to offer are workaround procedures.