If a host-only adapter cannot be created, either with the or the VBoxManage command, then the INF cache is probably corrupt. In this case, the install log at %windir%\inf\setupapi.dev.log would typically mention the failure to find a suitable driver package for the sun_VBoxNetAdp component. Again, as with the bridged networking problem described above, the solution is to uninstall , remove the INF cache (%windir%\inf\INFCACHE.1), reboot and try to reinstall .