Internet Connection

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I'm with Supanet & they recently advised to download critical software from Microsoft to protect from a virus which I did, but now I can't get a connection (dial-up) for Internet & e-mail without huge problems. Can't connect & Error boxes appear telling me that my ISP can't be found. Another connection box appears & once clicking on that I eventually get through, but I now no longer have permission to go onto my homepage which I did before (something about proxy permission) Can anyone tell me what I should do? I've not changed any pass words etc, just downloaded protection ware from Microsoft.