Http://clx.im popup can be clarified as an adware and it is very harmful, and some technicians has claimed that adware can be the sources of all security related issues on your PC. Http://clx.im popup is brought by the third party application or spam email, porn websites. no matter what suspicious sites or freeware occur on your PC, you get chance to have adware on your computer.
Http://clx.im popup is able to hijack your browsers first. That is to say, your browser settings can be changed and your information can be stolen. It will make up the fake ads carrying on the most superficial frauds. But as it happens frequently, you will easily believe in it or it will change your mind sometimes.