I hope someone can help with this. Im having a problem with what seems like a piece of malware, but which is behaving in way thats very hard to understand. My Macbook is on Mountain Lion. I work across two wifi systems, one at home, one at work. The home one is new (to me I didnt set it up), as Ive recently moved house. A week or so after moving to the new house I started to get what looks like Flashback popping up in my browsers (Ive tried with different browsers it affects both Chrome and Firefox). It blocks access to some sites such as YouTube and Google Books, and generally makes the browsers difficult to use. Its extremely frustrating. Ive run the Terminal test described here, as well as the test on flashbackcheck.com. Both say the computer is clean. Since Flashback, most of the tools related to it and media stories about it date from 2012, at first I just thought that I had caught a new version of Flashback which evaded the tests. Perhaps thats the case. But heres the odd thing: on the work wifi, the computer behaves normally I have no problems accessing anything I want. The malware is a problem only at home. Over roughly the last week, thats been the clear pattern. Can anyone explain whats happening? How can I remove a piece of malware that I appear to have, but which the tests say I dont? And why would its behaviour be affected by which wifi Im using? Thanks in advance.