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:
This is how I mananged to fix this problem:
Enable "Windows 8" compatibility for VirtualBox executable: right-click on VirtualBox shortcut>Properties: in Properties dialog box: switch to "Compatibility" tab, under "Compatibility mode" section, select the check box next to: "Run this program in compatibility mode", make sure "Windows 8" is selected in combo box. click Ok, run VirtualBox again! (it's not needed to run as Administrator)
p.s.: It seems that VirtualBox doesn't yet fully support Windows 10, so some features might not work properly on some computers