Information on Browser Hijacking.
Browser Hijacking is when 3rd party software (software that is not written by a Trusted source such as “Micro$oft”) gets accidentally or forcefully downloaded from visiting certain websites. Over time you may have noticed that there are more things gathering at the top of your internet explorer browser, now some of these things are alright to have but some of these come from a 3rd party such as Mywebsearch.
The best way to get rid of those nasty browser hijacking bugs is to visit
htto://www.merijn.org/
and download yourself a copy of hijack this.
they also have a very nice archive of other free tools available for download.