While i go to a lot of trouble to make sure that the programs used and the advice given here is bulletproof, you cannot hold me responsible for any loss damage or corruption caused by following any advice given or installing and running any of the software recommended on this site. However, it is the way i run my PCs (i have 5 or 6 altogether at home) so I'm not suggesting anybody do anything that i wouldn't do.
Messenger and other chat programs are a big source of problems for people, mainly due to our natural urge to trust that what people say is true, unfortunately, on the internet, people can say whatever they like and no one can really tell if it is true or not. People say all sorts of things to trick young people into believing their stories. The motives are not always good and the results can be catastrophic. Parents find this problem very difficult, especially with teenagers however i think you should make a firm stand and demand to know who every single person your child is chatting to. You need to be able to identify where this person is from, are they a relative or a school friend, a church friend or a sport friend etc, if they aren't they need to be taken off the list, its that simple, if you cant see this person in the flesh it can be hard to know whether they are telling the truth or not.