When I upgraded to Avas 4.6, a message came upp that Microsoft Outlook has blocked Avast. I tried to reinstall the Office package and then Avast, but it still doesn’t work. Though Outlook is open and working, a message in Avast Scanner says: The provider is waiting for a subsystem to start".
Make sure the avast plugin is not disabled into MS Outlook:
Outlook 2003 > Help > About > Disabled items
Outlook 2000 > Tools menu > Options > Other > Advanced Options > Add-In Manager.
The message “The provider is waiting on the subsystem to start” will be shown there until you open MS Outlook.
The plugin will be enabled automatically after that.