[Solved] HELP | Installation failed! Error: Fatal error during installation.

[socratis]

1. Uninstall VirtualBox. Your VMs are going to be untouched. Reboot.
2. You may want to clean up your registry and/or filesystem at this point. CCleaner is a freeware utility that could help you. Mind the installation, it comes with "offers" from 3rd parties, known as "bundleware". Also, check out Device Cleanup program that helps you to remove any unused devices from your computer, mainly multiple "Host-Only Adapter #n".
3. Download (if you haven't already) the latest VirtualBox and its matching ExtPack. Store them in a common location, i.e. not on "Desktop", or "Documents", but to "Public/Downloads" for example.
4. Uninstall (don't simply disable) all 3rd party antivirus. If you're afraid about your computer being vulnerable, pull the Ethernet plug, disconnect your WiFi, don't go browsing around.
5. Locate the downloaded file in Windows Explorer. Right-click on the installer and select "Run-as-Administrator", even if you are the administrator. At the end of the installation, choose to "Start Oracle VM VirtualBox". Do not worry if your VMs do not show up.
6. If you're going to install the ExtPack, go to File » Preferences » Extensions. Click on the icon with the orange, down-pointing arrow on the right. Select the ExtPack from the previous steps.
7. Quit VirtualBox. Re-start VirtualBox as you would normally, i.e. from the Desktop shortcut or the Start menu.
8. Update the Guest Additions (GAs) in your guest(s), if the GAs are available for a specific guest.

[Tommex]

I followed your steps, My heart was beating as soon as I saw the window of success, Thank you very much guys.
I don't know why but maybe registry was full of virtualbox old trash? or maybe the other option is Malware bytes blocked something at the installation even if disabled.
Again, thank you so much!

[socratis]

I don't know why but maybe registry was full of virtualbox old trash?

Nope. Even if it was, they get overwritten.

but IMHO this is clearly a permissions issue, i.e. the OP does not have permission to install device drivers.

It was mpack's suggestion. Typically, an administrator has the right privileges to install the VirtualBox drivers. For example, on my 3 Win* PCs I never had the need to use the Run-As-Administrator trick, when I'm logged in as Administrator. But, we've found that this is not the case in some systems, and they need the Run-As-Administrator trick. No clue why.

Maybe it was indeed the Malwarebytes that hardened the security in the device registry keys. Haven't done a thorough study.

Glad you got it going. Marking as [Solved].

[BillG]

I suspect that the people who have trouble with admin privilege on installs are users who have non-standard UAC settings. If UAC is working as intended, you will get a prompt if you are running an admin account and need admin privilege. If you have tampered with the UAC settings, you may not.

[mpack]

I think it's been a long time since "I have admin rights!" was a binary on/off thing in Windows, i.e. not since Win98 really, and especially since Vista. Now it's a collection of security policies, each of which can be turned on or off for a particular user. I think "Run as administrator" tweaks them all to a more permissive state, temporarily of course.