One of our readers Kapil reported that his computer has been infected with chost trojan. Because of this trojan certain web-sites are not opening. This kind of problem can also be caused by trojan.vundo .
Although this is a old known trojan, so your anti-virus software should have virus-definitions to take care of this trojan. But even if the anti-virus software has cleaned the trojan, the chances exist that you will still face problem in opening web-sites.
This is so because this trojan modifies your windows “hosts file” and makes certain web-sites point to a local host. Such web-sites will not load until this host files is corrected.
Let us see how take care of the trojan and fix the hosts file.
To fix the trojan, update your anti-virus software virus-definitions and run a full system scan. To see additional tips on protections against viruses, see this post.
Once you run a scan and clean the computer of the trojan, half-job is done. For rest half, you need to correct the host file. Go to location
and open the host file located at this path with Notepad.
Delete all the contents of this file and type the line below
Save and close this file. Restart your computer. Done!
But if you are still facing problem, it can also be because of DNS servers problem, see this link for solution.