issues:
Failed to open a session for the virtual machine ubuntu.
Raw-mode is unavailable courtesy of Hyper-V. (VERR_SUPDRV_NO_RAW_MODE_HYPER_V_ROOT).
Resul
You need to disable the windows Hyper-V feature and bcd. Then Virtual Box will run in latest Windows 10 versions (Jan-Mar 2018). Windows 10 Hyper-V is having clash on VirtualBox features.
I have resolved this by following steps-
bcdedit /set hypervisorlaunchtype off
Disable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All
Detailed discussion on this are available at - https://forums.virtualbox.org/viewtopic.php?f=6&t=87237
Alternatively you can install linux (Ubuntu) in Windows 10 from the latest bash command - https://www.windowscentral.com/how-install-bash-shell-command-line-windows-10