The Messaging Engine failed to register an adapter "HTTP". Details: "Registering multiple adapter types within the same process is not a supported configuration. For e.g. HTTP and SOAP receive adapters cannot co-exist in the same process"

This error happens as a result of sharing an application pool with another adapter, particularly a web service, which conflicts with the configuration of the AS2 adapter. As is breifly described in this MSDN article, if this error occurs, consider separating a separate application pool for each adapter.