Hi,
you forgot two calls:
before calling IComponent::setActive(false) you need to call IAudioProcessor::setProcessing (false).
and after calling IComponent::setActive (true) you need to call IAudioProcessor::setProcessing (true).
And normally a plug-in is only allowed to call IComponentHandler::restartComponent from the UI thread. But we already saw plug-ins doing it whenever they want.
Cheers,
Arne