virtualbox.org

Hi,

I recently installed VirtualBox on my Ubuntu 17.04 / Dell Precision 5520.
For installation I used the command (as advised on this german page: wiki.ubuntuusers (dot) de/VirtualBox/Installation/ )

I was warned that it would need to deactivate Secure Boot on my laptop in order for it to boot up any VMs (I checked, indeed it didn't work).
After installing and rebooting, a new screen popped up, asking me for a previously entered password in order to deactivate Secure Boot. Note, this was not a dialog of my UEFI, but from some tool that must have been installed alongside VirtualBox.

Now, after having removed VirtualBox I still get the message "Booting in insecure mode" on every startup of my laptop. However, when entering my UEFI Secure Boot is enabled.
Who can I trust? If my UEFI is wrong, how can I reactivate my Secure Boot? I tried reinstalling the same VirtualBox packages but the screen for activating/deactivating Secure Boot did not show up again.

I hope anyone of you can help me with this as I'm at my wit's end.

virtualbox-qt and virtualbox-dkms are forked packages from your Ubuntu distirbution, not from the official Virutalbox release.
Please ask in the Ubuntu support forums as we here don't have an idea what they are doing with these packages-