No internet access in browser

[emoke_margit]

Hello!
I have a problem with my internet connection but don't know if it has to do anything with me or with my ISP, as they are not willing to help.
The problem started at my office: I can use Yahoo Messenger, listen to online radio, download, but all of my browsers (FF, IE, Google Chrome) display the 'Server not found' error, even for google.com. This problem appears 3-4 times a day, lasts 10-15 min, then I can browse again. I tried two different Belkin routers but the problem still persists. I assumed maybe the problem was with the Belkin routers, until the same problem appeared at my home too 3 days ago, although the router's (Asus) configuration wasn't changed (it has been working perfectly for over 1 year - since I last configured it) nor was my laptop's.

Please, could anyone point out what the cause of the problem is, because the ISP isn't too helpful.
Thank you!

[flagstar]

It could be from your recently installed software and may accidently installed toolbar which some of it do block browser from surfing...

If others internet-related programs works fine, then something is blocking your browser from surfing the web...

[emoke_margit]

Hi!
I have only MSN toolbar, Yahoo toolbar, Skype toolbar and uTorrent toolbar. But I don't think they could be the cause, as the same problem is happening on my co-workers laptop too.

[cocolio]

check if the work offline option in file menu is cheked

[flagstar]

Scan your computer for malware with THIS , install it, update it and then run full scan. Post the log here if possible.

Also you could try IE without any addons running to prove that toolbar is not affecting your browsing problem...
Go to Start -> All Programs -> Accessories -> System Tools -> Internet Explorer (no addon)

[emoke_margit]

No, this can't be malware related. I have made a few experiments:
1. when problem appears, I can't get to google.com by typing in the domain name in the browser, but if I type in the IP address of google.com it works
2. when problem appears I can not ping google.com, but I can ping the google server IP address
3. when problem appears nslookup www.googgle.com is not working, when problem disappears nslookup www.google.com is working

My conclusion is, it is a DNS server error caused by my ISP. Now I changed the network adapter's DNS address to Google's DNS server and have to wait and see if this solves the problem for now.

Is my conclusion right? Would need a second opinion before I call the ISP to explain them what the problem is, as in my opinion they don't even know what a DNS server is.

[flagstar]

If using IP address instead of address itself works, it could be something blocking it. Like I said, it could be malware but I can't cross out that your ISP were also the culprit...

It won't hurt doing a scan although it do take hours to complete but you can call your ISP first to confirm the problem... If they still saying it's not their problem, then try other internet alternatives and see if that works...

[emoke_margit]

I did a scan, as you advised, here's the log:

Time elapsed: 1 hour(s), 45 minute(s), 13 second(s)

Memory Processes Infected: 0
Memory Modules Infected: 0
Registry Keys Infected: 0
Registry Values Infected: 0
Registry Data Items Infected: 0
Folders Infected: 0
Files Infected: 2

Memory Processes Infected:
(No malicious items detected)

Memory Modules Infected:
(No malicious items detected)

Registry Keys Infected:
(No malicious items detected)

Registry Values Infected:
(No malicious items detected)

Registry Data Items Infected:
(No malicious items detected)

Folders Infected:
(No malicious items detected)

Files Infected:
c:\$Recycle.Bin\s-1-5-21-3292051177-2126132970-433201939-1000\$RFKDUPD\Alcohol.exe (Trojan.Agent) -> Quarantined and deleted successfully.
c:\program files (x86)\alcohol soft\alcohol 120\Langs\AX_RU.dll (Malware.Packer.GenX) -> Quarantined and deleted successfully.

[jingda]

Is that a malwarebytes scan, why does it seems so weird. If you know how to use combofix the right way if you do not know do not use it. Does other laptops or computers have the same problem as you when connect to different networks? Have you try resetting the router? Download and run this software .

From what you stated and have tried out. It seems like a positive DNS Server error. Very rare but still happens. Go to network connections and in TCP/IP properties. makre sure your DNS server is properly configured.

Edit:

Maybe this link will help you

http://support.microsoft.com/kb/814591

[emoke_margit]

yes, it's a Malwarebytes' Anti-Malware scan.

Yes, this happens to other computers connected to the network.

We have reset both routers we tried multiple times, but didn't solve it. Neither did resetting work on my home router. The problem persisted, until after 10-15 minutes suddenly (without any modifications to laptop or router) I could access pages from the browser again.

TCP/IP properties: the DNS server was set to automatical, but last night I changed it to use Google's DNS servers (8.8.8.8 and 8.8.8.4) and since that I had no problems.

But still it's not a solution to set the DNS server of every computer connecting to the network. That is why I need a confirmation of my theory/conclusion, so I won't look like a dumba*se if I call the ISP and demand a resolution or cancel my contract with them.

[jingda]

When you configure the DNS server to Google DNS server, does other website work or only google. Just to clarify, does the problem occur on most websites you visited. If changing the DNS server work, the same could happen to your colleagues computer. A spyware accidentally downloaded to the internet, can affect one computer but it does not spread so i am puzzled by your problem too. Try using another computer and change the DNS server too. If it works and the computer is fine, it seems like a DNS problem.

[emoke_margit]

By using Google's DNS server I can view any page, in fact I can even play videos on youtube, something that was impossible before.

Yes, every time the problem appeared I couldn't view any pages: mail.yahoo.com, wikipedia, etc. No page worked at all.

My colleague, who is away for a month now, is using a UK ISP now, and had no problems with his machine since he left. This makes me assume it's not software, spyware, malware or TCP/IP configuration related.

[jingda]

So when he is using a UK ISP there is no problem. He can view all websites like normal. How about other people. If they use other ISP and are having no problem, your ISP is mostly the cause of the problem. For your work network and home network, are you using the same ISP for both?

[emoke_margit]

My ISP is the most commonly used here, so I don't know about anyone else having the same issues with different ISP's. We tried all the machines here (different brands, having as OS Win XP or Win 7) and had the same problem.

Yes, I have the same ISP at home and in the office, but of course using different accounts to access internet.

What I heard is that one local company received a notification from the ISP, about setting their DNS server address manually and providing them the address's.

[jingda]

Maybe that your problem too. You have to manually set the DNS server address on all affected computer. Is your ISP willing to help, maybe they can change all the dns server at one time. call them

[emoke_margit]

The 'tech' guys at the ISP are id*ots. All they can say it has nothing to do with them and I should figure it out.

Anyway now that I am certain this is caused by them (since last night, when I set the DNS server manually, the problem didn't reappear at all) and give them a call or cancel the contract.

Thank you very much for your replies and help!

[jingda]

You are welcome, maybe if those guys at the ISP do not offer to help, just find a better ISP and cancel the contract. Good luck