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I am desperately seeking some help for a big problem in my PC with Windows 7 cable connected to an ADSL modem. Since a couple of days ago I noticed this very strange behaviour: just after a new system boot, I can surf the web as usual with my browser. But after a couple of visited pages (not more), internet slows down and becomes virtually impossible to use.

The only way to temporarily recover internet use is to reboot PC from scratch (disconnecting as user doesn't work). But even so, after a couple of click, internet becomes unusable.

I made many tests to try to understand more about the problem:

  1. I tried with different browsers (Chrome, Internet Explorer, Opera, Firefox) but the progressive slowing down is always present (so it is not a problem of browser);

  2. on another PC with Ubuntu connected to the same Digikom ADSL modem-router, internet works fine as usual (so it doesn't depend on my internet connection); I tried also to change cables and connections, with no result;

  3. as I have a old image of my system, I reloaded it with Norton Ghost to see if the problem depend on some recently installed software or virus: but after loading previous image, the problem was again there as before;

  4. I tried to reset the modem with the reset button, but that too didn't solve the problem (so it doesn't depend on modem);

  5. I booted the PC from a Linux Disk and in this way internet is working OK (so it definitely depends on Windows 7).

That's all and I am completely puzzled. Even a little suggestion, some idea, everything would be greatly appreciated.

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3 Answers

I suspect some spyware filling your computer's memory and making it behave like having too little RAM. Running anything in normal mode will not help much as some spywares detect a scanning program and try to stop it or copy themselves elsewhere to restore at next startup. So you think you have removed them and they are right back at next reboot.

How to fix it properly:

Reboot the PC and press F8 just before seeing the Microsoft logo. This will activate the advanced startup menu from which you select Safe Mode with networking support. This way almost no spyware will run and you will be able to access the internet to download the necessary tools (plain Safe Mode doesn't activate the network cards, so you cannot access the internet). As long as you are in Safe Mode, browse the internet for www.spybot.info and download Spybot Search and Destroy. Install it and of course update it before searching. Then search for spywares and remove all results.

Then I would also try Malware Bytes Antimalware from www.malwarebytes.org Same again, download the free version, install it, update it and make a full scan. Remove everything found. Last step is to manually uninstall any unwanted application (eg Uniblue Driver Scanner 2013 etc) from Control Panel, Programs and Features. Some applications might complain that cannot access the Windows Installer Service in Safe Mode. No worries, you can uninstall them when back in normal mode.

Before rebooting your PC to normal mode, you must check the startup list so no unwanted services or programs start when Windows start. This will speed up your PC a lot and will also reduce the risk of running a spyware upon startup. To do that press WIN+R (WIN is the windows key, between CTRL and ALT) to see the Run dialog. Type MSCONFIG and press ENTER to execute it. Go at the services tab, check the "Hide all Microsoft services" checkbox and then examine all remaining services carefully. Uncheck any single one you don't need. If any program doesn't work properly because of a disabled service, most likely it will state the service's name, so you can go back at MSCONFIG and check the box again to enable it. Then go at Startup tab and examine all entries carefully. You can safely disable (uncheck) updaters (eg Google update) and other programs (eg Windows Live Messenger, Skype etc) you don't need at Windows startup. There is no use loading Skype automatically when starting Windows. If you need Skype, you can manually start it by using its shorcut on your desktop or programs. This way Windows will start faster and respond better. Be extra suspicious for unknown programs that are in C:\Windows\System32. Most times they are definitely a spyware or virus and must be disabled (I would also browse to the folder and delete the relevant file). After you finish with MSCONFIG you may restart and let Windows start in normal mode. First time after MSCONFIG you will see a message, check the box not to appear again and click OK.

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I'd have to agree. –  Griffin Feb 20 '13 at 1:44
    
I followed step by step all your precious suggestions and first of all I discovered that, while in safe mode, web surfing is going on at full speed. By the way pressing F8 doesn't work, I don't know why. To boot in safe mode I have to power off PC - not very recommendable I know - and then reboot: so I can see the startup menu with safe mode with networking option. I looked for malwares as suggested and found nothing. I disabled all services except system ones and rebooted. Again web surfing is OK. So thank you very much for helping! –  Giancarlo Feb 20 '13 at 10:59
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This is most likely the result of some pesky piece of Adware. Remove any toolbars you have and then run a scan with Spybot and if that doesn't help, Malwarebytes.

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I'll try this too, but it seems to be quite unbelievable that there were the same malwares in my old recovered system image too.... –  Giancarlo Feb 19 '13 at 22:15
    
Viruses, and to a lesser degree malware, love hiding out in old system restores. It can make it a royal pain to be rid of them. –  David Feb 19 '13 at 22:27
    
@Jikag - looks like he was using a Ghost image. It is unlikely that a even a particularly nefarious virus would have made it's way in to a Ghost image, at least in my experience. –  AJ Henderson Feb 20 '13 at 4:56
    
@AJHenderson You may be right, I've never used Ghost Image, so I assumed that it worked just like System restore. –  David Feb 20 '13 at 14:33
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Try a virus and malware scan from a LiveCD. If they don't find anything, I would suggest rebuilding the IP stack. You can delete your network connection from network devices and delete the NIC from Device Manager. When you reinstall it, it should rebuild the network stack and if any configuration settings or driver issues had come up, it should help clear out any wackiness.

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I rebuilt my IP stack following suggestions on Microsoft site, but this didn't solve the problem. Thanks for your idea... but I still need help! –  Giancarlo Feb 19 '13 at 22:14
    
If rebuilding the IP stack from scratch didn't work, then it is probably an active piece of Malware. Best bet, LiveCD it with up to date definitions. If you find a virus, backup your files, nuke it from orbit and start over. Otherwise, if there is no virus found, I honestly have no idea what else it could be. –  AJ Henderson Feb 20 '13 at 4:55
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