Well: in the Avast On Access Scanner: at the Outlook Exchange page there is a remarkeble line:
The provider is waiting for a subsystem.... does somebodies bells are ringing?
No, this is not the problem...
The plugin, like any other plugin, will be disabled until you open (run) MS Outlook.
If MS Outlook is running and the plugin disabled you should:
1. Enable it into MS Outlook like I try to say before.
2. Start the avast provider (click on the 'a' blue icon and start it...)