My brother-in-law Felipe had looked at our desktop computer and replaced the power supply unit.
Stella brought it home and tried to hook it up to ADSL the way it had been, but couldn't get it to work.
I tried connecting via WLAN, and couldn't manage at first. Also, trying to access the configuration was a bit puzzling, since Windows kept telling me that a property sheet was open and so it couldn't show me everything, which was puzzling.
Apparently, I was connected to the WLAN but had no IP address... all the entries in that property sheet were blank, not even "0.0.0.0" or something of the sort. (Not blank, but some text in angle brackets.)
One restart later and things appeared to work... I could my NTP client updated and I was able to access our WLAN router through its web interface. But when I clicked the second link, my MSIE froze up.
I started Opera, but that froze, too, upon starting. Tried starting Firefox: nothing visible, though it was in the Task Manager's process list. Bizarre.
Try to shut down -- didn't work, because some programs were hanging. Even force-quit didn't seem to help. So I switched the computer off completely.
Something got broken somewhere along the line... ever since then, the computer will get part-way along the way to starting up, then spontaneously reboot (I can hear the fan going to full speed again) and I'll get the screen allowing to me boot in Safe Mode, from Last Known Good config, or normally.
I tried Safe Mode in order to disable the WLAN adapter, in case that was the problem, but the configlet thingy couldn't find its hardware and refused to talk to me.
I tried Last Known Good, and that took quite a while, and the interface was a bit funny -- instead of the blue rounded title bars, for example, they were grey and rectangular. After a while, my desktop came back, at least, with the icons on it.
One reboot-and-a-half (the "half" being the spontaneous reboot...) into Last Known Good later, things look normal again (except that my task bar was one unit high, instead of two). Logging on also went quickly again. Switched off the WLAN adapter and rebooted -- still no dice.
This sort of thing is incredibly frustrating, when I don't know what to do to fix things (especially if I suspect that I did something to break things). For some reason, I can't handle having people around me in that sort of situation, at least until I've "cooled down" a bit from my frustration.
This is all incredibly annoying.
And I have no idea how to fix this, or whom to ask to fix it. I don't know whom to trust when it comes to repairing computers, because they can be complex and fiddly and I don't want someone who doesn't have experience and won't simply reinstall Windows or something. (I was briefly tempted to do so, but I don't know whether I'd be able to get all the drivers for the installed hardware back running, since the system came pre-installed.)