two things.
1. get rid of your file sharing proggie. every computer i ever installaed kaza in got really screwed. if you must use a file sharing proggie, use something open-source, such as nucleus (which if far better than kazaa imho).
2. dont look at porn or warez sites. they tend to use few ethics in their web programming. if you must try to get an old version of netscape (the one that was out before it started sucking anything < version 4 works fine). ie is ok so long as the page your looking at is reputable. once you go evil, your pretty much screwed.
i used to manufacture computers and when peopke had software problems, most of them eighter used kazaa or were full of porn. also try to avoid free programs that are full of ads. they mey tell you what teperature it is outside and keep your clock uber accurate, but they tend to make sure your screen is full of ads. and some ads contain ilicit code.