Most computer users don't know what they are doing and unintentionally download stuff. When they see it ask if they want to install such and such program when visiting a website, many people think that they have to download it to see the website (which is not true in most cases).
Perhaps a little education instead of yelling would help.
Of course, if she installed Kazza, AIM, YIM!, MSN, ICQ, IRC, Bonzi Buddy, changed your desktop, and filled your hard drive with mp3's, changed your home page in your browser, and subscribed you to a bunch of junk mail lists, well, then... I'd be pissed to.
