Hi - I'm new here and have come across your post whilst searching for an answer to this very problem. After an Avast update this weekend, all my computer settings were wiped exactly as per your description above and many of programs would now not run. I have accounts and payroll software running on this computer and they were not usable until Avast was uninstalled from the computer. Spent the afternoon on the phone to IT to try and get things operational again. Wasn't a windows update that caused the problem, almost certain it was Avast.