I am unbelievably stupid.
Some background; my computer has a weird intermittent hardware problem where, upon boot, something happens to the network card. I’m not sure exactly what goes wrong, but when it does, the computer knows it HAS a network card, but is unable to do things like acquire an IP address from DHCP. The problem seems unfixable once it’s occurred; the only solution is a reboot. However, this isn’t a big deal, since it usually only takes 3 or 4 reboots to get working again, and I can identify the problem early in the boot phase.
So, tonight I opened up my PC to put in a new video card (which then came back out; another story entirely), set everything back up, turned on my PC, and there was the error. Not even thinking, I just hit reset, because that’s what I do when I see that error. The next boot, error again. I rebooted about 10 times and the error kept happening. At this point I got worried, so I powered the machine off and decided to let it rest a little bit. I spent the next 5 hours messing with the computer, on and off.
I tried everything I could think of: I opened it up and reseated the cards, I did software reboots, hardware resets and hard power downs. I let it wait a little while, I let it wait a long time. I left it on for an hour and then did a reset. I reconfigured the network card, I read through the logs for hints. Nothing worked. Then I looked over, and saw it. The network cord. Was not. Plugged. In.
At least I’m back online now.