Their has been a large number of these coming up lately and the vast majority of them are not really the result of true viruses, but rather the effect of an exploited BHO (browser help object). Browser Help objectsd can perform useful functions such as redirecting pages that you dont want to be accesed or offering similar pages to the one which you are trying to access if that page cannot be found. Unfortunately they can also be used to autoredirect to porn-sites or other undesirable content without permission (not that porn in undesirable but its "PC" to say it is and god forbid if anyone says anything that isn't strictly politically correct). I recommend downloading BHODemon and using to reveiw the browser help objects installed on your system. It can be found here: http://www.definitivesolutions.com/bhodemon.htm