Black screen upon starting up Kubuntu

[Tom H]

>>>>>> At blank screen (after attempting to boot as usual), press
>>>>>> 'alt' + 'ctl' + 'prt scr' + 'k'

>>> No need for ctl.

>> Didn't know that. I'll try it on reboot. Thanks.

> Okay, done. But it has to be the *right hand side* alt key.
> Using Left hand side alt reboots again. (I guess that's how Keith got back
> to rebooting).
> Thanks again Tom, something new.

You're welcome.

I have never heard of a right-side-alt+sysrq+k combination. I have
just tried it and it behaves exactly like alt+sysrq+k for me; the SAK.
What keyboard layout do you use?