Can’t Browse Web, Can Ping and E-mail

Thursday, 2009-September-24 at 01:50 1 comment

This one is here so I can find it easily next time. I spent most of a day troubleshooting this before I found the solution.

User cannot browse the Web. May be able to browse secured (https) sites, but normal (http) sites blocked. Can ping sites. Can use an e-mail client. Can use Telnet, except for port 80.

  • Check firewall settings, anti-virus, anti-spyware, anti-malware. Run full scan with your security software.
  • Check proxy settings.
  • Connect another computer to see whether there is something filtering out HTTP upstream.

Done all that already? So had I. Then I found this, which led me to this.

Here’s what you can try next:

  1. Reboot the computer into safe mode. If you don’t, you won’t be able to do this.
  2. Log in with a local machine administrator’s account. Open the registry editor.
  3. Navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\vsdatant and set Start to 3. NOTE: if this key isn’t there, this isn’t your problem and this fix will not help you.
  4. Restart the computer.

In this case, you’re probably dealing with the leftover pieces of a ZoneAlarm firewall installation.

As the HP discussion site above says:

1. Even if you think you never installed ZoneAlarm (like me), still look out for vdatant.sys, it may be there!
2. You cannot change the registry setting when vdatant.sys is loaded/running, even if you have Admin privileges. You need to boot your machine in safe mode (with or without networking), and then you can edit the registry setting to disable the driver.

Entry filed under: Software. Tags: , , .

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1 Comment

  • 1. Bob  |  Thursday, 2009-November-05 at 19:54

    I had a problem with WIN/XP IE8 being unable to go to http: sites also and this is what it happened to be, similar to yours with NIS..

    Earlier that day I’d installed Avast! and that turned out to be the high water mark for my memory usage. Afterward the computer was so slow due to maxed out memory that while it was still coming up I’d cancel unessential auto-started programs (AIM, Paltalk, spyware programs, etc). I cancelled Avast as it was coming up, too, and that’s what caused me to lose ability to browse http sites. Evidentally Avast! blocks http (port 80) until it’s fully started, but since I cancelled it before it could naturally complete it never got the chance to open port 80 again. Ergo no access to http sites even though I could get to https sites OK (port 435). I suspect the registry is updated somehow like NIS and something like your solution to NIS would have worked. I uninstalled Avast! and rebotted and everything worked OK.

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