That's the culprit. Since you have Windows as Host, it's probably Pro level or above, which has an RDP server. This prevents VB from using it's VRDP server, that's available in the extpack you just installed. Disable VRDP and things will go better. If that doesn't help, change the port number to which VRDP listens. The default is 3389, the same Windows RDP uses.