Boy, that's a loaded question! Does viewing porn make the viewer want to go out and rape? And what is the definition of porn? Personally, I have never viewed porn, unless you wanna count Playboy and I always read the articles
Being a rape survivor myself, I know it's an act of violence. But do violent movies cause violence? Give me a nice romantic comedy any day of the week.
Of course anything on the internet can be addictive (duh, clipmarks) and if you are taking away time from your family to fuel your addiction, then it's a problem.

it seems sometimes that the Internet, the concept became, the all to be blamed...