I just upgraded my laptop from Windows 7 to Windows 10 and found that I am unable to start Virtualbox VMs configured with a bridged adapter.
See the configuration below:
In Case some one is looking and none of the above resolves your issue : https://forums.virtualbox.org/viewtopic.php?f=6&t=90650&p=434965#p434965
placing the WIFI as the first adapter [MTDesktop, AllowALL] and the LAN WIRED [MTServer,AllowAll] as the second adapter. In the Guest machine I disable the First Adapter in Adapter Settings. I can then ping internal, external whatever.