openSUSE release: 42.2.20161212 clean & fresh installation
installed on Virtual Box version 5.1.12 r112440, host system: Windows 7
Enterprise 

With a default kernel parameters, namely:
resume=/dev/sda1 splash=silent quiet showopts
when I reboot the system, it hangs. When it is turned off, it starts normally,
but the problem appears when I want to reboot it. According to site
https://en.opensuse.org/SDB:Debugging_boot_hang I changed the parameters to:
resume=/dev/sda1 debug initcall_debug

I expected the system to hang during printing information to the console, but
it didn't. It hanged just after entering the graphical mode. And this is the
reason, why I chose "KDE Applications" as the Component.

Interestingly, when the system hangs and I choose "close" or "reset" option in
Virtual Box, Virtual Box hangs together with openSUSE.

It is worth mentioning, that I have found workaround. According to this site:
http://superuser.com/questions/1077342/opensuse-hanging-on-boot I used
resume=/dev/disk/by-uuid/the_proper_uuid instead of resume=/dev/sda1. After
that it doesn't hang.

I wanted to capture the screen, to show you how it hangs, but unexpectedly,
when I turn on capturing screen feature in Virtual Box, the system doesn't
hang. In the attachment openSuse.webm you can see the debug and initcall_debug
information when system reboots.

Regards,
Piotr