I have several computers, all running Win 10 with free Avast, also mostly having the same installed programs. Just one machine seems to have an issue with Avast, in as much as the notification area icon is there after boot-up but the second I hover the cursor over it (no clicking), it vanishes. If I click on the desktop icon, the main interface won't come up, so I obviously can't access anything in the settings or program, but the notification area icon re-appears. I have tried a "repair" and also a complete uninstall, using the special tool, and a re-install, with the same result. I have also tried running as administrator from the desktop icon and "AvastUI.exe" from the program folder, but the circle rotates a few times and nothing else happens. Trying from safe mode gives the same symptoms. Any thoughts, folks?