How come iTunes stopped working after I ran software that was supposed to make my computer run faster?

Q: I recentsly used some software that is supossed to “make my computer faster”. And now iTunes will not open. Every time I try to open it, my whole computer frezzes and I am forced to hold the power button to shut it down. I have a 6 month old, HP, quad core that has windows 7. How can I get iTunes to work again?