A new kind of dial-up internet hell.
June 23, 2008 2:11 AM   Subscribe

Archaic Windows dial-up networking question; why do I randomly lose internet connectivity (with dial-up still online) and can't get it back without restarting the computer?

OS: Windows Vista

Due to a recent move to an internet black hole (Tasmania), we've had to resort to dial-up internet. We've been having a problem where we will randomly (as far as we can tell) lose network connectivity. Browsers (Firefox, IE, Opera, whatever) will no longer access sites, saying the sites "Exist but cannot be reached".

Similarly, other software (Yahoo messenger, Putty!) will also refuse to connect.

However, if I open up a command prompt, I can happily ping, nslookup, tracert without a problem.

Killing the dial-up connection and redialing doesn't help at all. Rebooting the PC fixes the problem 100% of the time.

I've tried disabling the only thing I can think of that might cause a problem, the anti-virus software (Avast!), but that doesn't help.

Any ideas how I can diagnose this problem? Why would every program that accesses the internet claim it can't connect, but low-level command-line utilities can?
posted by Jimbob to Computers & Internet (11 answers total) 1 user marked this as a favorite
if it's not a laptop, I'd suggest it's some sort of IRQ problem.
posted by so_ at 4:41 AM on June 23, 2008

nslookup, ping and tracert are all UDP or ICMP based. If there's something in the machine that's broken TCP, those three tools would continue to work but browser connections wouldn't.

Try using telnet on port 110 to connect to a mail server. If that works, try it again on port 80 to connect to a web server (trickier because you need to get the syntax of a web request right before you'll see a response from the other end). If the telnets don't work, you're probably seeing a misconfigured firewall, or the remains of one.

I know you've got Avast now, but are you sure there's no trace of any other "security" software left on the box? I've seen precisely the behavior you're describing after incomplete removals of Zone Alarm and Norton Internet Security. If Norton has ever been anywhere near this machine, try running the Norton Removal Tool against it to see if that improves matters. If it used to have Zone Alarm, reinstall ZA and then do a clean uninstall.
posted by flabdablet at 4:56 AM on June 23, 2008

By the way, I don't think an IRQ problem would break TCP-based stuff but leave UDP and ICMP alive. Seems to me that an IRQ problem would be more likely to break networking altogether.
posted by flabdablet at 4:57 AM on June 23, 2008

Response by poster: I will try flabdablet's suggestions, although I'll have to wait for the problem to return. Avast is the only "security" software on the machine, apart from the standard "Windows Defender" or whatever they call it.
posted by Jimbob at 5:04 AM on June 23, 2008

i have exactly the same problem, but with broadband internet. Torrents still download (in utorrent) but i cant visit any websites.
posted by freddymetz at 5:19 AM on June 23, 2008

In my experience, Windows Defender causes more problems than it corrects. If I were experiencing what you are on a machine with WD installed, I'd certainly try turning it off.
posted by flabdablet at 6:02 AM on June 23, 2008

Jimbob, if you email me a Hijack This! log, I'll scrutinize it for clues.
posted by flabdablet at 6:04 AM on June 23, 2008

Response by poster: Thanks, flabdablet, will do.
posted by Jimbob at 2:16 PM on June 23, 2008

If the problem is resolved, could you please post the cause?
posted by freddymetz at 4:10 AM on June 24, 2008

Jimbob, this line

O23 - Service: Ad-Aware 2007 Service (aawservice) - Lavasoft - C:\Program Files\Lavasoft\Ad-Aware 2007\aawservice.exe

says you have the Ad-Aware anti-adware service running. If you weren't already aware of that and hadn't already tried turning it off when the problem occurs, try doing that. If you don't have enough of Ad-Aware still installed to turn it off with Ad-Aware's own GUI, you should be able to stop and disable it using the Services management console (right-click My Computer, select Manage, drill your way down to Services and follow your nose).
posted by flabdablet at 5:35 AM on June 24, 2008

Response by poster: Aah I forgot about Ad-Aware, thanks, I'll give it a go.
posted by Jimbob at 3:43 PM on June 24, 2008

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