JWs have never been officially instructed to not use the Internet. I have heard individual JWs comment however that it would be better if JWs avoided the Internet altogether rather than take chances...whatever those chances might be.
JWs have been storngly cautioned about reading anything negative about the WTS on the Internet. They've warned to avoid bulletin boards, chat rooms, blogs and the like where any kind of negative information about the WTS could be easily or accidently accessed.
Some dubs that I know use the Internet as much as any non-JW that I know, but manage to never give a thought to typing "Jehovah's Witnesses" in Google or any other search engine. I know one dub who gets his porn on-line, steals music on-line but he's loyal about never reading anything about JWs or the WTS on-line.
But I know some other dubs who won't have a computer in the home...period. One dub family member had a computer with Internet access so they could email friends and family all over. After a while there was a problem with the computer. Another family member, non-JW, told them that something was wrong with the hard drive and needed to be replaced. She offered to back up the system, install a new drive and reload the info. But before taking her word the JW got a brother from the hall, supposedly PC savvy, to look at it. He said it had a virus and the Internet needed to be disconnected. The JW relative immediately thought apostates were trying to infect their computer and got rid of it. They refuse to own a computer, let alone have Internet connection, anymore.
I'm sure that it was never said from the platfrom that apostates would use computer viruses to attack God's people...but they do demonize the Internet so much that those who don't really understand computers, the Internet, etc. come away with notions that the Internet, or computers even, or evil and must be avoided...exactly the result that the WTS wants.
The WTS may be able to scare the older generation away from the Internet, but younger generations who learn computer skills and Internet skills at an early age, won't be so easy to buffalo. It will be interesting to see what the next generation or two of young dubs who know more about this technology than their parents will bring.