I agree with the sentiments expressed so far:

The Internet is NOT to blame for simply being the medium through which dangerous individuals are introduced to children. For this reason, banning children from chat rooms will not solve the problem - they will simply ignore the bans anway. As Karen mentioned, many sites have a restriction for under 13's, but there is no reliable method to "prove" that you are older than 13.

What it boils down to is simply BAD PARENTING. Many parents these days have divorced themselves from the timely methods of parenting. Instead of interacting with their child, educating him/her about the world and shaping his/her behaviour, parents are now simply dumping their teens in front of Playstations and computers with access to the Internet. In this fast-paced world where many women are forced to work to provide the essential second income, so few have the time or energy to be good parents. Worse still is the ever-growing army of "spoilt brats" who have never been taught decent behaviour for the same reasons.

Parents should never blame society, the Internet, or any other outside factors when their child is lured into a dangerous situation by a stranger UNLESS they tried their very best to educate their child about the dangers involved and tried to monitor his or her behaviour online.