I wanted to give a shot to keyscrambler >>> system wouldn't boot anymore after the install, not even in safe mode, so I tried "last known good". This worked. Then I attempted to uninstall keyscrambler >>> uninstall failure. So far nothing to do with Avast. So I launched a system restore, in safe mode, rebooted once again in safe mode >>> system restore was successful. Rebooted in normal mode >>> dark screen and empty task bar in Windows >>> I knew it was Avast somehow >>> rebooted in safe mode, uninstalled AIS from there, rebooted in normal mode >>> no problem. I admit I didn't deactivate the self-defense module before launching the restore (in other conditions it wouldn't even have been possible), BUT AVAST 5 SHOULDN'T PREVENT SYSTEM RESTORE IN WINDOWS FROM WORKING PROPERLY ANYWAY >>> it's been like that for a while, and it's still not solved.