I wanted to update VirtualBox from 5.2.28 to 5.2.34.
When I update VirtualBox I first update the host side and then update the Guest Additions in all virtual machines (VMs). I have been updating VirtualBox in this manner since the 1.x Innotek days.
Updating was status quo until I attempted to update a Windows 2000 VM. The VM abruptly died with a
Stop 0x0000006B PROCESS1_INITIALIZATION_FAILED blue screen of death (BSOD).
Some quick reading around the web indicated the likely suspect was drivers.
I restored the host system to version 5.2.28. Removing and reloading VirtualBox kernel modules would not allow me to start the Windows 2000 VM. I had to fully reboot the host computer.
After rebooting I again was able to start the Windows 2000 VM. I then updated to the 5.2.34 Guest Additions before updating the host.
That seemed to resolve the BSOD when I updated the host to 5.2.34.
Oddly I had no problem updating NT4 and XP VMs.