Need an HDMI cable.
Recall having one around here somewhere.
Dig around: nope.
Wait, see if it's plugged into the back of the office monitor: yup.
Unplug it, and try to pull it free of the computer kennel: nope, not comin' outta there.
Workstation is due for a software update that looks like it'll call for a reboot. So:
Do the apt-get upgrade, and shut the workstation down.
Pull the workstation out, look behind it, and eventually find the other end of that HDMI cable.
Which has a DVI connector on it. Which (a) explains why it was so hard to pull through the cable clump, and (b) isn't exactly what I was looking for, but maybe will do.
So, pull the cable through the other way, and put everything back together.
Reboot the workstation.
Text display during bootup has colored sparklies.
DVI connection to back of workstation wasn't properly secured. With the jackscrews tightened, the sparklies go away.
Kdm thinks it starts up, but there's no X display.
Startx gives an error log that seems to say that it can't find a connected monitor.
OK, so re-configure the DVI cabling so the workstation's output goes directly to the monitor, bypassing the DVI switch (which isn't currently used anyway, what with the second workstation being retired).
Still doesn't work.
Boot the previous kernel: nope.
Fiddle around some more: still no soap.
About ready to panic here... has my software configuration gotten horribly broken? On the last day of the month, when I ought to be doing Accounts Receivable this evening? Will I have to use my laptop until I can get this sorted out?
Maybe if I boot some runs-from-CD distro...? Pop the April edition of Kubuntu into the drive, and tell the BIOS to boot from it.
Hey, wait. Could unplugging the HDMI cable have...
Once more unto the breach 'twixt desk and wall, narrow and cable-beclutter'd though it be.
Ah. I hadn't tightened the jackscrews on the DVI connection to the monitor, a couple of years back. When I unplugged the HDMI cable, I must have jostled it.
OK, tighten the jackscrews, reset the workstation in midKubuntuboot, and boot normally.
Well, looky here: kdm starts, and the X display comes up as normal.
And what I needed the HDMI cable for? Maybe I'll get to that tomorrow. Trying to diagnose some hardware that shouldn't need it, but maybe does.
Enough stress for now. Time for some mindless entertainment, assuming the living-room infosystems are still in working order.