Maybe need an upgrade? Check the wiki: https://sourceforge.net/p/vboxvmservice/wiki/Home/
Release version 5.2 - Jujube
Version 5.1 (Plum) - VBox since 5.1.16 not working
It works well with VBox 5.1.22 here. The problem must be somewhere else.
Works well with VirtualBox 5.1.10 here. The problem must be somewhere else.
VMVirtualbox 5.1_(Plum) unable to start VirtualBox 5.1 (guest)
cannot connect to VMs via Remote desktop