virtualbox.org

First of all, thanks to everyone contributing to this community. I have found some really good explanation posts here.

My Ubuntu-20.04 VM on VirtualBox 6.1.16 has suddenly stopped working and I am not sure of the reason.
It's showing the booting Ubuntu logo and at the moment where it's supposed to show the login screen, it is showing a blinking underscore with a distorted cursor.
I have tried a bunch of solutions but none of them seems to work. Maybe someone else can have a look the log file suggest something.

Specs:
- Host: 64-bit Windows 10 Home Single Language
- i7 8750H 2.2 GHz, 4 Cores, 2 given to Ubuntu VM
- RAM: 16 GB, 10GB given to Ubuntu VM
- Video memory: 128MB, 64MB given to Ubuntu VM
- Graphics Controller on VM: VMSVGA with 3D acceleration enabled
- Storage: VBoxGuesAddition.iso 60MB, 50GB dynamically allocated storage

The guest is probably working, it is just very, VERY slow, because you have Hyper-v enabled on your host.

00:00:03.694408 HM: HMR3Init: Attempting fall back to NEM: VT-x is not available
00:00:03.792243 NEM: WHvCapabilityCodeHypervisorPresent is TRUE, so this might work...

For how to disable Hyper-v, see the last post in FAQ: I have a 64bit host, but can't install 64bit guests.

In other news, you are dangerously close to exhausting host RAM, and have not assigned enough graphics RAM. I suggest you reduce VM RAM to 8GB, and increase graphics RAM to 256MB.