This site is for the co-ordination of the Ubuntu project(s), not support. Sorry.
If this were a problem with Ubuntu (it’s not), I would gently direct you toward https://community.ubuntu.com/t/finding-help/712 to see Ubuntu help options.
However, your problem seems clearly with the Windows version of VirtualBox, which Ubuntu does not provide support for. We gently suggest you try VirtualBox’s support channels.