If you're getting redirected to random advertisement pages each time you search on Google & other search engines, then the likelihood is that you have a virus on your PC that's causing this problem. The "Google Redirect Virus" is a very damaging and common infection, but is actually very easy to remove if you have the right tools and methods.
The "Google Redirect Virus" is what's known as a "browser hijacker" as it installs itself onto your computer and then proceeds to change a variety of important files and settings that your browser needs to run. The virus then changes your browser so that when you search for something online, it will just redirect you to some random advertising websites. This virus is normally accompanied by the many "rogue antivirus" viruses that often infect computers.
7 Google Android Tablet
How to remove it...
If you have this virus on your PC, there is an easy and a hard way to remove it. The hard way (which many people end up doing) is to look around constantly for an antivirus program which can remove this virus from your PC. However, there are no actually many antivirus tools which are able to do this as this virus just edits and corrupts certain files and does not behave in a typical sense.
The way to fix this issue is to use the right antivirus tool to remove the Google Redirect Virus from your system. There are a few effective tools which can fix this issue, and in order to get rid of it for good, you should download one of these tools, install it and then let it fix the files that are damaged by the virus.
You also need to use a "registry cleaner" tool to scan through your computer and fix any of the errors or damaged files that might be inside the registry. Many computers that are infected with the Google Redirect Virus keep getting it back because they don't clean out the settings it leaves inside the 'registry' database. Registry cleaners clean out the registry database of Windows (the central storage facility for all the settings inside your PC) and then fix any of the corrupt or damaged files that are inside it.