Fixed today, please restart your PC
Whilst I haven't experienced this problem on XP or win10 systems, despite having rebooted win10, the registry key has a MicroUpdates entry, but there is no 356= number.
The 356=1526391120 number is present in my XP registry entry, but the regkey location is different HKEY_LOCAL_MACHINE\SOFTWARE\AVAST Software\Avast\MicroUpdates.
That system however hasn't been rebooted today.