I have a recurrent problem with Windows 7 on my Dell computer. For several times now, the homepage and the default search engine changes to MixiDJ; some pops-up appear, such as: Fix PC errors now! or 1 click PC fix; various ads appear all the time; various unwanted windows open why I am trying to open some internet site. Also, it keeps telling me that my media player needs an update and invites me to do so, but, it seems to me, this is a fishy message. It seems to me that the problem comes back when I try to see some video, it prompts me to update my video player, and I do that, or even some first step of that. I got help for a couple of times in restoring my computer to normal, the problems comes back every now and then. How can I fix the problem myself?