I recently installed Avast Free 15 and, after a few days, its shields shut off. I tried to re-establish them with no luck, so I uninstalled the program and reinstalled Build 2015.10.0.2208. I don't know which version I had installed about a week ago, and don't know if the shield problem was a one-off incident nor what might have caused it to occur. So far, it hasn't recurred, and Avast Free's as well as a recent Malwarebytes' scans do not reveal any malware, so I hope the problem has been cured. I would like to know, though, if anyone has heard or experienced any similar behavior, or might have a suggestion as to what happened. Thanks.