Children have free access to pornography.
2) Makes people too lazy to refer books.
3) Wastage of time by kids and adults on internet chatting.
4) Internet can give false information on certain subjects which makes books a better option. (eg: some ''wiki'' articles are not reliable)
5) Cyber friendships sometimes lead to extreme dangers like kidnaps, rapes etc, when both parties meet in person.
6) Virus attack is a major problem.
7) Internet gaming gives people long time exposure to computer screens and bad sitting posture which can lead to various health problems.
8) Extremely addictive.