Since GTA there has been a lot of controversy about violence in games and the media have made links between violent incidents/shootings and video games, but these are unfounded. The gov in the US has told media outlets to stop doing it because there is no evidence to suggest that Video Games any more influential than movies, music or art. Ever listen to NWA? Or have you seen SAW?
I saw in interesting article about this from the US in where a study called Violence and Gender, found that video games decrease the likelihood of producing hate material online and researcher Jim Hawdon says "this finding suggests that violent video games may serve as an outlet for aggression, not a precursor."
Internet addiction, or compulsive screen time is a real concern to mental health though, no matter what you are looking at or doing online.