A web hijacker is a program that will redirect your webbrowser to different sites (generally with no user action). They will sometimes change your homepage and refuse to change it back. Read my security tutorial I wrote here and try the Spyware programs I suggest and see how that works. (Mainly Ad-Aware and Spybot are the ones you're going to want to try.) Let me know how that works.
"Personality is only ripe when a man has made the truth his own."