The DNS (Domain Name System) servers are what your computer uses to figure out where to go on the internet. www.whatever.com means absolutely nothing to your machine. It's only with the help of the DNS servers that your computer can figure out what address that domain name correlates to.
There are several methods of hijacking the DNS entries on your PC. The most common, and easiest way to do it is to add false entries into your computers HOSTS file. We'll cover how to empty that out first:
The HOSTS file is located in a couple of different locations, depending on your Windows version. In Windows XP it is located at C:WINDOWSsystem32driversetchosts (no extension). In Windows 98/ME it is at C:Windowshosts (also no extension).
Open it up with notepad. The contents of the file should look like this:
# Copyright (c) 1993-1999 Microsoft Corp.
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
# For example:
# 188.8.131.52 rhino.acme.com # source server
# 184.108.40.206 x.acme.com # x client host
If there are any entries below the localhost one, then unless you've added some on purpose, then you've more than likely been hit with a DNS hijacker of some sort. The best course of action here is to run a full system scan with an up to date virus scanner, as well as a couple of spyware scanners. (Preferably from safe mode)
After the scans are done, then use WinSockFix to repair the corrupted WinSock settings. This should take care of the problem.
Kevin Souter is a full time computer repair technician. He also operates a free spyware removal site, as well as a general computer repair site.