More and more frequently, users are reporting unwanted changes in the behaviour of their web browser. Changes that might be seen are:

PUP means “potentially unwanted program”. It’s an extra piece of software that’s included when a user downloads or updates another program or application. A PUP is different from malware, because the user agrees to download it. If you download a program from the Internet without reading the download agreement, or without carefully reading every installation screen and check box before clicking the “Next” button, you might not realize what other unwanted programs are being downloaded. Downloading popular software from other than the official website is a particular danger.

The PUP is often an add-on/extension/plug-in installed in your browser. PUPs can be many things — search engines, toolbars, shopping advisors, coupon sites, or ad fetchers, for example.

The quickest way to check whether your problem is caused by a browser add-on or extension is to disable add-ons/extensions and see if the problem goes away. To disable add-ons/extensions:

Firefox Safe Mode:  (Firefox >) Help > Restart with Add-ons Disabled

Chrome:  Opening an Incognito window disables extensions.   > New incognito window

Internet Explorer: > Manage Add-ons > Show: All add-ons then select add-ons one by one and click Disable

Safari:   > Preferences > Extensions > OFF

If you do find that disabling add-ons solves the problem, you'll need to track down the add-on responsible and disable or uninstall it.

Sometimes the PUP identifies itself, so you can often find a solution to your problem by using Google to search for [ remove name ], where name is the name of the unwanted search engine, shopping advisor, etc. Beware of suspicious search results — you shouldn't need to purchase or download special software to fix the problem.

If you use Google Chrome browser, this help article might assist:

Other steps you should take are:

If you feel uncomfortable or unqualified to fully investigate this issue, I suggest you enlist the services of a competent and trusted computer technician.